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K


K is the eleventh letter of the , named and pronounced /ˈkeɪ/ in English. It generally represents the phoneme /k/, produced by raising the back of the tongue to contact the and releasing a burst of air. The letter traces its origins to the , meaning "hollow of the hand" and shaped like an open , which evolved into the (Κ) before adoption into the . In early Latin, K served alongside C and Q to denote /k/, initially used before a, but its frequency declined as C assumed most duties, relegating K to rare occurrences in native words and preserving it chiefly for loanwords, abbreviations, and proper names. This historical redundancy explains K's sparse appearance in English vocabulary compared to C, with modern usages often signaling emphasis, as in "," or denoting quantities like "k" for in scientific and technical contexts.

Etymology and Historical Development

Proto-Scripts and Semitic Origins

The , recognized as the earliest ic writing system, originated around the 19th century BCE among -speaking workers in turquoise mines at in the . These inscriptions adapted using the acrophonic principle, where signs represented the initial consonant of the name for the depicted object, creating a consonantal suited to . For the voiceless velar plosive /k/, the Proto-Sinaitic sign derived from the hieroglyph for an or arm (Gardiner sign D46, depicting the ), selected for its initial /k/ sound in the Proto-Semitic word *kapp- (" of the hand" or " of the hand"). Early forms of this resembled a pictographic open , emphasizing its iconic basis in the physical shape of a hand. This adaptation marked a shift from logographic-syllabic writing to a purely consonantal system, enabling more efficient recording for lacking Egyptian's vocalic complexity. Evolving through intermediate Proto-Canaanite variants between the 15th and 12th centuries BCE, the hand-derived sign standardized in the as kaph (𐤊) by approximately 1050 BCE. retained the /k/ and a simplified, hand-like form, facilitating its transmission via . In Proto-Semitic and daughter languages like Hebrew and , kaph denoted the /k/ sound, distinct from uvular /q/ () and other pharyngeals, reflecting accurate phonetic representation in systems. The name kaph, from *kapp-, directly evoked the motif, underscoring the script's mnemonic and semantic ties to everyday vocabulary.

Greek Kappa and Classical Adoption

The Greek letter kappa (uppercase Κ, lowercase κ) derives from the Phoenician letter kaph (𐤊), symbolizing the palm of the hand, as adapted by Greek speakers during the development of their alphabet in the late 8th century BCE. This adaptation occurred amid trade contacts with Phoenician merchants, transforming the abjad script into the first alphabetic system incorporating vowels, with kappa assigned to the voiceless velar plosive /k/. Early inscriptions, such as those from the Dipylon Oinochoe circa 740 BCE, demonstrate kappa's form stabilizing as a vertical stroke with arms extending rightward, reflecting its Semitic progenitor while suiting Greek phonology. In Classical (5th–4th centuries BCE), served as the primary for /k/, appearing before front and back vowels alike, as in kalos (beautiful) or kosmos (), without positional allophones altering its uniform articulation. This consistency contrasted with the aspirated /kʰ/ denoted by (Χ), enabling precise orthographic representation in authors like and , where 's frequency underscores its role in core vocabulary. Epigraphic evidence from vases and inscriptions confirms 's widespread adoption, with minimal regional variants persisting into the Hellenistic era. Kappa's numerical value in the system was 20, marked as Κʹ, facilitating calculations in and astronomy, as seen in Ptolemaic tables. Its form influenced subsequent Italic scripts, though prioritized phonetic fidelity over the digraphs common in Phoenician-derived systems.

Latin Retention and Medieval Evolution

In , the letter , inherited from the Etruscan and ultimately , was retained as part of the 21-letter but saw sharply diminished usage after the early period. Initially in inscriptions around the 7th-6th centuries BC, K represented the /k/ sound specifically before /a/, complementing C (used elsewhere except before /u/, where Q prevailed) to avoid redundancy with the undifferentiated /k/ and /g/ sounds. By the , following the differentiation of /g/ via the new letter (derived from C), C was universally adopted for /k/ across positions, rendering K archaic and superfluous except in fixed forms like kalendae (the , marking the month's start) and rare Kaeso. This retention preserved K's symbolic presence in the alphabet, though its phonetic role was effectively supplanted, with classical texts containing fewer than a attested instances, primarily in archaizing or contexts. Medieval Latin continued this pattern of marginal utility for K, confining it to abbreviations (e.g., Kal. for kalendis), proper nouns evoking antiquity or origins (such as Karolus for Carolus in some Carolingian-era documents), and occasional emphasis in or legal manuscripts to distinguish from softened C pronunciations emerging in . The 8th-9th century Carolingian reforms under of standardized minuscule scripts for clarity in monastic copying, evolving K's form from the open, angular uncial and half-uncial variants of —characterized by a detached upper bow—to a closed-loop uppercase and a simplified lowercase k with a looped ascender and straight , facilitating faster pen strokes while maintaining legibility. This minuscule k, appearing rarely in texts like bilingual charters, often featured a wedged or looped top in insular influences, reflecting regional adaptations in Anglo-Saxon or continental scriptoria. By the high and late Middle Ages (11th-15th centuries), K's shape further diversified in Gothic textualis and cursiva scripts, with angular, broken strokes and shortened diagonals in English and manuscripts, yet its frequency remained low—less than 0.5% of /k/ representations in sampled corpora—due to entrenched C dominance and the rise of vernacular orthographies that variably reintroduced K for native /k/ sounds absent in Romance evolutions. Retention ensured K's inclusion in pedagogical lists and liturgical books, preventing total obsolescence, while causal factors like scribal economy and phonetic stability favored C; however, revival in occasionally prompted retentions in transliterations, subtly evolving K toward philological utility.

Modern Standardization

The modern form of the letter K was standardized during the through the widespread adoption of movable-type , which fixed letter shapes in metal typefaces and minimized scribal variations prevalent in medieval manuscripts. Johannes Gutenberg's development of the around 1440 enabled mass production of texts with consistent glyphs, drawing on for lowercase and capitals for uppercase forms. This uniformity spread rapidly after 1455 with the printing of the , influencing typographic practices across Europe. The uppercase K maintained its classical configuration—a vertical intersected by two diagonal strokes creating right angles at the top and bottom—revived in humanist typefaces like those cut by punchcutter Nicolas Jenson in 1470, which emulated ancient inscriptions for legibility and aesthetic fidelity. The lowercase k, originating in 8th-century Carolingian with a closed upper loop and descending leg, became entrenched in printed works, evolving minimally thereafter to its current stem-loop-leg structure seen in fonts from to . In the 20th century, international standards further codified K's representation. The American Standard Code for Information Interchange (ASCII), finalized in 1963, assigned uppercase K the decimal value 75 and lowercase k the value 107, ensuring portability across early digital systems. The , part of standards like ISO/IEC 646 from , formalized the 26-letter inventory including K for global interoperability in data processing. These encodings persist in (U+004B for K, U+006B for k, adopted 1991), supporting consistent rendering in digital typography.

Phonology and Orthography

Phonetic Representation

The letter ⟨K⟩, in its primary phonetic role across many alphabetic writing systems including the , denotes the consonant, articulated by raising the back of the tongue to contact the (velum), building up air pressure behind the closure, and then releasing it abruptly without vocal cord vibration. This sound is transcribed in the International Phonetic Alphabet () as , with IPA number 109, and is a fundamental stop found in the phonemic inventories of over 85% of the world's languages. In , ⟨K⟩ consistently represents the /k/, as in words like "" (/kaɪt/), "" (/skaɪ/), and "back" (/bæk/), where it contrasts with other graphemes like ⟨C⟩ (before ⟨a⟩, ⟨o⟩, ⟨u⟩) or ⟨CK⟩ in final positions. The realization of /k/ in English is typically aspirated ([kʰ]) word-initially or post-pausally (e.g., [kʰaɪt] for ""), unaspirated intervocalically or after /s/ (e.g., [skɪ] for "ski"), and may exhibit velar softening to [kˠ] or affrication near front vowels, reflecting allophonic variation governed by phonetic context rather than orthographic inconsistency. Historically, in , ⟨K⟩ encoded the same /k/ value as ⟨C⟩ and ⟨⟩, though its usage was restricted primarily to loanwords or abbreviations, with no phonemic distinction—all rendered as without aspiration, as Latin lacked the voiced counterpart /g/ distinction in early orthography before G's introduction around 300 BCE. In modern derived from Latin, ⟨K⟩ remains marginal but retains in internationalisms (e.g., "kilogramo" in ), while Germanic and employ it more frequently for /k/, often with uvular allophones in dialects like or . Acoustically, features a brief (closure phase) followed by a burst of frication around 2-4 kHz, with transitions varying by adjacent vowels—rising for front vowels (e.g., /ki/) and falling for back (e.g., /ku/)—enabling perceptual cues for . This representation persists in phonetic transcription systems beyond , such as (⟨k⟩), underscoring its universality despite orthographic redundancy in languages like English where ⟨C⟩, ⟨K⟩, and ⟨Q⟩ overlap for /k/.

Usage in English

In , the letter consistently represents the phoneme /k/, articulated by raising the back of the tongue against the to briefly obstruct . This contrasts with , which denotes /k/ before a, o, u, or consonants but shifts to /s/ before e, i, y, necessitating in positions like keep, kit, and sky to preserve the hard /k/ sound. appears primarily at the onset of syllables or words, especially in Germanic, , or derivations (e.g., , , kinetic), and less frequently word-finally except after long vowels or consonants, as in or desk. A convention, known as the "CK rule," applies when /k/ follows a short at the end of a monosyllabic word or : it is spelled CK to indicate the doubled consonant sound, as in back, , or , preventing with single after vowels. Conversely, K alone follows long vowels, diphthongs, or consonants (e.g., book, milk, walk—though walk uses L for the /k/ via historical ), and CK is avoided in multisyllabic words or after non-short vowels, yielding forms like or attack. Exceptions occur in proper nouns or borrowings, but adherence to these patterns aids predictability in instruction. K is occasionally silent, particularly in the digraph at word beginnings, as in , , and know, a remnant of where the /k/ was pronounced but later lost in standard by the . This /k/ sound is spelled with K about one-fourth as often as with C across English texts, reflecting historical preferences for Latin-derived C in many core vocabulary items. Among English letters, K ranks low in frequency, comprising approximately 0.69% to 0.87% of letters in representative corpora of 40,000 words or similar samples, placing it behind (12.7%) but ahead of rarer letters like (0.11%) or (0.07%), due to /k/'s common representation via C and reduced use in native Anglo-Saxon roots. This scarcity influences applications like or , where K's positions (often initial or final) carry strategic value.

Usage in Other Languages

In , the letter K appears infrequently, mainly in loanwords, international terms, and proper names, where it uniformly represents the /k/, akin to its English but without variation. In , K is extremely rare in native vocabulary, with examples limited to borrowings like kilómetro (pronounced /kiˈlométɾo/) and kárate, as native /k/ sounds are typically spelled with C or Qu. French follows a similar pattern, employing K sparingly—primarily in words like kilo or karaté—and pronouncing it as , identical to the hard C before back vowels, though influence reduced K's role in favor of C and Qu for /k/. Italian and exhibit comparable restraint, reserving K for foreign elements such as kilogrammo or quindici variants in technical contexts, maintaining /k/ without positional softening. Germanic languages utilize K more prominently for native /k/ sounds, distinguishing it from C, which is largely confined to Latin-derived or foreign terms. In German, K denotes /k/ in common words like Kind (child) and Kalt (cold), with aspiration ([kʰ]) more pronounced than in English, while C appears in scholarly borrowings like Caesar. Dutch mirrors this, employing K for /k/ in everyday lexicon (e.g., kat for cat), with minimal use of C except in proper nouns or abbreviations. Scandinavian languages vary slightly: Swedish and Danish use K for /k/ in words like katt (cat), but Norwegian and Icelandic feature palatalization before front vowels (e.g., Norwegian kylling with soft [ç] akin to German ich), reflecting historical umlaut influences without altering the letter's core velar role. In adopting , such as and , K consistently represents /k/, forming a staple of native without digraphs for or softening, as in Polish kot (cat) or Czech kůň (horse). Turkish, using a Latin-based alphabet since , employs K for /k/ in both native and loanwords (e.g., kedi for cat), with frequency elevated due to phonemic reforms prioritizing over etymological C variants. Across these languages, K's low overall frequency—often under 1% in Romance texts versus higher in Germanic—stems from historical Latin preferences for C/Qu, yet its phonetic stability endures in modern usage.

Orthographic Conventions and Variants

The Latin letter adheres to standard bicameral conventions, distinguishing between uppercase —characterized by three straight strokes forming an angular structure—and lowercase k, which typically includes a vertical with a looped ascender and a diagonal extending below the in most typefaces. Uppercase is mandated at the start of sentences, for proper nouns, and in acronyms per English language standards, while lowercase k appears in medial and final positions within words. In cursive handwriting, uppercase K retains a blocky, printed-like form with minimal flourishes, often starting from the top line and descending with angled legs, whereas lowercase k involves an initial upstroke from the to the midline, a small returning to the , and a final diagonal downstroke to form the leg. These forms promote and flow in connected , with variations across styles like or Zaner-Bloser emphasizing smoother joins for the lowercase. English orthography employs K specifically for the /k/ sound before front vowels e, i, or y (e.g., "keen", "kite"), reserving C for other contexts to avoid ambiguity, a convention rooted in historical Latin influences but adapted for phonetic clarity. Following short vowels at word ends or in monosyllables, the digraph ck is standard (e.g., "lock", "tick") to reinforce the voiceless velar plosive, preventing confusion with softer sounds. Silent K precedes n in initial clusters like "knee" and "knight", preserving etymological roots from Old English and Germanic sources despite non-pronunciation. Typographic variants include serif extensions on the legs of K in fonts like for enhanced readability in print, versus the unadorned geometry in designs like , which prioritize uniformity. Specialized forms, such as the small capital ᴋ in or the reversed in certain linguistic notations, deviate from baseline orthography but appear in technical contexts like the .

Symbolic and Practical Applications

Scientific and Technical Designations

In physics, the uppercase K designates the kelvin, the (SI) base unit for , where 0 K marks , the theoretical minimum temperature at which thermal motion ceases. Temperatures in omit the degree symbol and use a capital K, such as 273.15 K for water's or approximately 310 K for . This scale, proposed by William Thomson () in , sets the Boltzmann constant's value to exactly 1.380649 × 10^{-23} J/K, linking macroscopic thermodynamic properties to microscopic particle energies. In chemistry, K symbolizes , element 19 on the periodic table, a soft essential for biological functions like signaling and . The notation derives from "kalium," the term rooted in "al-qalyah" for plant ash, from which was isolated in 1807 by , prioritizing continental European naming over the English "potassium" (symbol P already taken by ). Uppercase K also denotes the in chemical reactions, quantifying the ratio of product to reactant concentrations at under standard conditions. The prefix kilo-, abbreviated as k or K, signifies multiplication by 1,000 (10^3) in scientific and technical contexts, as in kilometers () or kilojoules (). In data storage, K represents kilobyte (), equaling 1,024 bytes in systems, a convention from early to approximate powers of two. Lowercase k frequently appears in physics for proportionality constants, such as the spring constant in (F = -kx) or Coulomb's constant in (k ≈ 8.99 × 10^9 N·m²/C²). In biology, K abbreviates , an with the codon AAA or AAG. Spectrometry employs K for specific spectral lines, particularly in for transitions.

Abbreviations and Numerical Prefixes

The letter K functions as a numerical prefix primarily through its role in the , where the lowercase k denotes the "kilo-" multiplier of 10³, equivalent to one thousand. This prefix, derived from the Greek χίλιοι (khílioi) meaning "thousand," was adopted during the establishment of the in in 1795 and later standardized in the (SI). Examples include the kilometer (km), representing 1,000 meters, and the kilogram (kg), the SI base unit of mass equivalent to 1,000 grams—retaining "kilo" for historical reasons despite the base unit convention. In informal and commercial English usage, uppercase K independently signifies "thousand," as in "5K" for 5,000 or "$100K" for 100,000 dollars, a convention popularized in the 20th century in , , and to abbreviate large numbers efficiently. This derives directly from the kilo prefix but deviates from strict SI lowercase convention for prefixes in non-technical contexts. Beyond numerical applications, appears in domain-specific abbreviations. In chemistry, K is the elemental symbol for , adopted from the Latin kalium (referring to ), a soft with 19. In physics and , uppercase K denotes the , the of where 0 marks , defined since 2019 as exactly 273.15 kelvins below the of . In computing, K combines with B for (KB), traditionally 1,000 bytes in decimal contexts or 1,024 bytes (KiB) in binary-aligned systems per IEC standards. Other technical uses include K for in statistics, tracking a batter's failure to hit three strikes.

Sports, Gaming, and Colloquial Symbols

In , K denotes a , a system devised by journalist Henry Chadwick in the 1860s while developing early box scores for the . Chadwick selected K, the last letter of "struck," after reserving S for sacrifice hits. A backward-facing K distinguishes strikeouts on called third strikes from those involving swings. In chess algebraic notation, abbreviates the king, the central piece whose capture ends the game. This convention aids concise recording of moves and positions, with the white king starting at e1 and black at e8. , especially first-person shooters, employ K for "kill" in metrics like the K/D , calculated as kills divided by deaths to player performance. A above 1.0 indicates more kills than deaths achieved. K also signifies thousand, as in "10K" for 10,000 units of currency, damage, or subscribers, derived from the metric prefix . Colloquially, in texting and online , standalone "K" functions as for "okay," signaling agreement or . Unlike fuller forms like "" or "okay," which appear neutral, "K" often conveys brevity, impatience, or dismissiveness depending on context.

Cultural Perceptions and Controversies

Literary and Psychological Associations

The sound /k/ represented by the letter K exhibits strong psychological associations with sharpness, angularity, and abruptness via . In the , first experimentally demonstrated in the early 20th century and replicated across cultures, over 70% of participants match the nonsense word "kiki"—featuring repeated /k/ and /i/ sounds—to jagged, spiky shapes, contrasting with the rounded forms linked to "bouba." This cross-linguistic pattern, evident even in pre-literate children and non-alphabetic speakers, arises from the plosive's , which mimics perceptual qualities of pointedness or hardness rather than arbitrary convention. Empirical research on phoneme-iconicity confirms /k/'s consistent linkage to spikiness and high in visual stimuli, with neural imaging showing prefrontal activation during implicit association tasks involving such pairings. These effects extend to semantic inferences, where /k/-heavy words evoke perceptions of , smallness, or , influencing and judgment; for instance, names with /k/ sounds are rated as more dynamic in hiring simulations. Such associations hold independently of , as demonstrated in studies comparing and non-Roman scripts, underscoring a perceptual rather than cultural basis. In , the K sound's phonetic qualities lend themselves to and consonance, evoking forceful actions or interruptions in and ; examples include alliterative clusters in English works like "knock" in Shakespeare's ("Knock, knock, knock") or explosive terms such as "kaboom" in modern narratives to mimic impact. Authors exploit this for rhythmic emphasis, aligning K's psychological profile with themes of or , though graphemic of the letterform itself remains underdeveloped compared to phonetic effects. Explicit literary motifs centering the letter are uncommon, with rare esoteric interpretations in non-Western traditions linking it to or transformative , but these lack empirical validation in mainstream analysis.

The OK Gesture Hoax and Media Response

In April 2017, users on the /pol/ initiated a coordinated trolling campaign known as "Operation O-KKK," aiming to convince outlets and the public that the common "OK" hand —formed by touching the thumb and index finger while extending the other fingers—secretly signified "white power." The hoax posited that the circle represented a "W" (for white) with the extended fingers forming a "P" (for power), explicitly designed as to expose perceived gullibility toward claims of hidden . The campaign gained limited initial traction, with some online posters ironically adopting the gesture, but it remained fringe until 2019, when isolated instances of its use by self-identified white nationalists, such as the Australian gunman Brenton Tarrant during his 2018 mosque attacks, prompted reevaluation. On September 26, 2019, the (ADL), a Jewish advocacy organization focused on combating and , updated its hate symbols database to classify the gesture as a potential hate symbol, noting that while it originated as irony, "at least some white supremacists seem to have abandoned the ironic or satiric intent" by then. The ADL emphasized context and intent, acknowledging benign uses but highlighting extremist appropriations in about 36 new database entries that year. Mainstream media outlets, including , , , and , widely reported the ADL's classification, often framing the as a newly recognized emblem of without consistently foregrounding its hoax origins or the rarity of malicious intent in everyday contexts. This coverage contributed to real-world consequences, such as the October 1, 2019, firing of a performer for posing with the in a photo, despite no accompanying , and investigations into U.S. cadets at West Point and Annapolis in December 2019, later cleared as innocent gameplay rather than signaling. Such responses underscored criticisms of overreach, as empirical data on usage showed no widespread shift to hate symbolism; surveys and analyses post-2017 indicated the vast majority of instances remained innocuous affirmations of approval, with hoax-driven amplification revealing institutional tendencies to prioritize narrative alignment over granular verification. The episode exemplified how anonymous online pranks could infiltrate credible discourse, with media and advocacy groups like the —despite their expertise in tracking genuine threats—sometimes conflating trolling with organic , potentially eroding in symbol-based threat assessments amid broader patterns of selective in polarized reporting. By 2023, lingering effects persisted, as seen in the firing of a soccer trainer for the gesture in a team photo, illustrating sustained hypersensitivity despite the symbol's dual-layered history.

Typographic and Character Relations

Ancestral Forms and Descendants

The letter K originated from the Egyptian hieroglyph for an , known as Gardiner sign D46 (𓂧), used in hieroglyphic writing as early as the BCE to represent the concept of a palm or hand. This pictograph was adapted by Semitic-speaking workers in the into the between the 19th and 15th centuries BCE, transforming into a simplified linear symbol for the /k/ and the acrophonic word kap(p), meaning "palm of the hand." From the Proto-Sinaitic form, the symbol evolved into the Phoenician letter kaph (𐤊) by around 1050 BCE, retaining a hand-like shape with a vertical stem and curved extensions symbolizing fingers. The Phoenician kaph, pronounced /k/, was borrowed by Greek scribes in the 8th century BCE as kappa (Κ, κ), which introduced a more angular, vertical design while preserving the /k/ sound. This Greek kappa influenced the Etruscan alphabet around the 7th century BCE, and subsequently the archaic Latin script, where K emerged in its modern upright form with two short diagonal arms by the 6th century BCE. The Latin K maintained this shape through monumental inscriptions like Roman square capitals, with minimal variation into the present day. The Phoenician kaph served as the progenitor for /k/-representing letters across descendant scripts, including Hebrew kaf (כ), Aramaic kaph, Syriac kaph (ܟ), and Arabic kāf (ك), all deriving through the Aramaic branch and retaining hand-inspired etymologies or forms. In the Greek tradition, kappa directly spawned descendants in Coptic (Ϭ for a variant sound) and indirectly influenced Cyrillic ka (К) via Byzantine Greek transmission in the 9th century CE. The Latin K persists in the Roman alphabet and its derivatives, such as English and other Indo-European languages, though its usage diminished after the 1st century BCE in favor of C for most /k/ sounds except before certain vowels or in loanwords; descendants include consistent /k/ notation in scientific nomenclature and non-Romance adaptations like Turkish k.

Ligatures, Abbreviations, and Diacritics

The letter K participates in few standard typographic ligatures, reflecting its low frequency in common Latin digraphs that might otherwise clash or require aesthetic unification, such as those involving f or s. Discretionary ligatures like "" or "ck" occasionally appear in custom or display fonts to enhance and visual harmony, as seen in implementations where they replace separate glyphs for improved in specific contexts. In historical Latin manuscripts, abbreviations employing K were uncommon owing to the letter's restricted role beyond words like "kalendae" (calends of the month), typically shortened to "K." or "Kal." with a stroke or superscript mark to denote . This practice aligned with broader medieval scribal conventions of and to economize space, though K's rarity limited its use compared to more versatile letters like C or M. Diacritics modify K to encode phonetic distinctions across languages and transliteration schemes. uses Ķ (capital) and ķ (lowercase) with a below to represent the palatal stop /c/, contrasting with plain K's /k/. employs ǩ with a for an alveolar palatalized /t͡ɕ/ or contextual /k/. Additional variants include ḱ () for acute /kʲ/ in romanizations or extensions, ḳ (dot below) in Indo-Iranian transliterations approximating emphatic /q/, and Ķ with or other marks in constructed scripts or legacy encodings. Forms like Ꝁ and ꝁ, featuring a horizontal stroke through the stem, historically abbreviated Latin "" (and) or served as insular variants in medieval texts.

Encoding and Representations

Computing Standards

In the American Standard Code for Information Interchange (ASCII), a 7-bit encoding standard developed in the 1960s and formalized by ANSI in 1968, the uppercase letter K is represented by value 75 ( 4B, 01001011), while the lowercase k uses 107 ( 6B, 01101011). These values position K as the 11th uppercase letter in the printable ASCII range (codes 65–90 for A–Z). Unicode, the dominant international standard for since its initial release in 1991 by the , assigns U+004B to LATIN CAPITAL LETTER K and U+006B to LATIN SMALL LETTER K, both in the Basic Latin block (U+0000 to U+007F). These code points ensure with ASCII, as the Basic Latin block mirrors ASCII values for the first 128 characters. In , the most widely used Unicode Transformation Format, these encode as single bytes matching ASCII: 0x4B for uppercase and 0x6B for lowercase. Extensions like ISO/IEC 8859-1 (Latin-1), an 8-bit standard published in 1987 by ISO for Western European languages, retain ASCII compatibility for codes 0–127, thus assigning the same values to K and k. In contrast, IBM's (EBCDIC), an 8-bit encoding originating in the 1960s for mainframe systems, maps uppercase K to D2 ( 210) and lowercase k to 92 ( 146), reflecting a non-contiguous ordering of letters that prioritizes punched-card legacy over alphabetic sequence.
Encoding StandardUppercase K (Decimal/Hex)Lowercase k (Decimal/Hex)
ASCII75 / 4B107 / 6B
(UTF-8)U+004B / 4BU+006B / 6B
ISO 8859-175 / 4B107 / 6B
(037)210 / D2146 / 92

Non-Digital Systems

In International , the letter K is encoded as dash-dot-dash (-.-), a sequence consisting of one long signal followed by a short signal and another long signal. This representation was standardized by the for global radiotelegraphy use since the early 20th century. In Braille, the letter K corresponds to the tactile cell with dots 1 and 3 raised (⠅, Unicode U+2805), forming the basic Grade-1 symbol derived from the 1829 system developed by Louis Braille. This configuration builds on the letter A (⠁, dot 1) by adding dot 3, maintaining consistency across the alphabetic series in the 6-dot cell. Flag semaphore represents K through arm positions holding red-and-yellow flags: the right arm extended horizontally forward (flag at 3 o'clock) and the left arm extended downward at a 45-degree angle (flag at 7:30 o'clock), as defined in 19th-century naval signaling codes later formalized for land and sea use. These eight possible flag positions per arm enable encoding the full alphabet without numerals in basic sets. The (ICS) designates the flag for K, a vertically divided (hoist) and () pennant measuring approximately 1:1.4 proportions in standard sizes, flown to phonetically spell "Kilo" or signal "I wish to communicate with you" in contexts since its 1900s codification by the International Maritime Organization's predecessor. In American Sign Language (ASL), fingerspelling K uses the dominant hand with palm facing outward, index finger extended vertically upward, and middle finger extended horizontally forward at a 90-degree angle from the index, thumb holding the ring and pinky fingers folded, as standardized in U.S. deaf education since the 19th century. In British Sign Language (BSL), K is formed by extending the index and middle fingers of the dominant hand into a bent "hook" shape (middle finger crossing over the index) with palm facing the signer or sideways, differing from ASL in orientation but serving the same alphabetic purpose in UK deaf communities. These systems prioritize tactile, visual, or auditory distinction for reliability in low-visibility or silent environments, such as operations or pre-electric communication.