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In

Indium is a chemical element with the symbol In and atomic number 49, classified as a post-transition metal that appears silvery-white and exhibits softness and malleability comparable to lead.^[1]^[2] Discovered in 1863 by German chemists Ferdinand Reich and Hieronymous Theodor Richter during spectroscopic examination of zinc blende ore, indium was identified by its prominent indigo-blue emission line, from which its name derives.^[2]^[3] The element is rarely found in native form and is chiefly extracted as a byproduct of zinc, copper, and lead refining processes, with global production concentrated in regions like China and South Korea due to ore associations.^[4]^[2] Indium's low melting point of 156.6 °C and chemical stability enable key industrial uses, including as indium tin oxide (ITO) coatings for transparent conductive films in liquid crystal displays, touchscreens, and solar cells, as well as in low-melting alloys, solders, and semiconductors for transistors and photoconductors.^[1]^[2] Its scarcity relative to demand—driven by electronics growth—has raised concerns over supply chain vulnerabilities, though recycling from end-of-life products mitigates some risks.^[2]

Grammatical and linguistic uses

Preposition and adverb

In English, "in" functions as a preposition to denote inclusion within spatial boundaries, as in "the keys are in the drawer," or temporal periods, such as "arriving in 2025." It also conveys means or medium, exemplified by "dressed in silk" or "communicated in code," and limitation or circumstance, like "equal in value" or "proficient in languages." Additional senses include purpose, as in "done in self-defense," and ratio or proportion, for instance "a chance in a million."^[5] These usages reflect "in"'s role in prepositional phrases that modify verbs, nouns, or adjectives to specify relations of enclosure, containment, or association, a function consistent since Middle English derivations from Old English. In modern corpora, "in" ranks among the most frequent prepositions, appearing over 3% of words in general texts due to its versatility in expressing internal relations.^[5] As an adverb, "in" indicates inward movement or direction, as in "step in" or "drive in slowly," or a state of being inside, such as "the plug is in" or "winter is in." It frequently combines with verbs in phrasal constructions to imply entry, involvement, or completion, including "fill in the form," "cash in the check," or "believe in the plan," where it alters the verb's semantic scope without an object.^[5] Distinguishing prepositional from adverbial "in" hinges on complementation: prepositional uses require a following noun phrase, while adverbial ones stand alone or precede objects in particle verbs, a pattern traceable to Proto-Germanic origins where spatial adverbs grammaticalized into prepositions.^[5]

Prefix and etymology

The English prefix in- denotes either inward motion or location ("in, into, on") in words such as inject and influx, or negation ("not, without") in terms like insane and inactive.^[6]^[7] The locative form originates from the Middle English in-, directly from Old English in- (as in in- + gangan yielding ingangan, "to go in"), inherited from Proto-Germanic *in- and Proto-Indo-European *h₁én ("in").^[7] This Germanic lineage parallels the adverbial and prepositional uses of in, with the prefix arising through conversion for compounding.^[7] The negative in-, by contrast, entered English via Latin-derived vocabulary, where it serves as a privative prefix meaning "not" or "lacking," often assimilating phonetically to im- (before p or b, as in impossible), il- (before l, as in illegal), or ir- (before r, as in irregular) to ease articulation.^[7]^[8] In Latin, this negating in- stems from an archaic Indo-European particle akin to *ne- ("not"), distinct in semantic development from the homophonous locative preposition in despite shared form; it contrasts with the native Germanic negative un-, which predominates in Anglo-Saxon-derived terms (e.g., unhappy versus inhappy, unattested).^[9]^[7] This dichotomy reflects English's layered borrowing from Latin and French during the Norman period, preserving etymological traces in word formation.^[9]

Scientific and technical uses

Chemical element

Indium is a chemical element with the symbol In and atomic number 49.^[1] It belongs to group 13 of the periodic table and is classified as a post-transition metal, appearing as a soft, malleable, silvery-white solid with a brilliant luster at room temperature.^[1]^[4] Indium was first identified in 1863 through spectroscopic examination of zinc ore concentrates, marking it as one of the elements discovered via this technique before isolation methods were refined.^[10] The element has an atomic mass of 114.818 u, a density of 7.31 g/cm³, a melting point of 156.60 °C, and a boiling point of 2027 °C.^[2]^[11] Chemically, indium exhibits a +3 oxidation state most commonly, forming compounds like indium(III) oxide (In₂O₃) and indium phosphide (InP), which are valued for their semiconductor properties.^[12] It is relatively stable in air but reacts with halogens and oxidizing acids; its softness allows it to wet glass surfaces, similar to gallium.^[4] Indium occurs primarily as a trace component in zinc sulfide ores such as sphalerite, from which it is recovered as a byproduct during zinc refining.^[13] Global production is dominated by China, with the United States consuming approximately 300 metric tons in 2023, mainly for industrial applications.^[14] Refined indium consumption in the U.S. reached an estimated value of $85 million in 2024, reflecting demand in electronics and alloys.^[15] Key applications include indium tin oxide (ITO) coatings for transparent conductive films in liquid crystal displays (LCDs) and touchscreens, low-melting-point alloys for solders, and compounds like InP for high-speed semiconductors and 5G technologies.^[14]^[4] Indium-113 is the sole stable isotope, comprising 95.7% of natural abundance, while radioactive isotopes like indium-111 find use in medical imaging.^[1] Supply constraints arise from its byproduct status, prompting recycling efforts to meet growing demand projected at a 5.47% CAGR through 2030.^[14]

Unit of measurement

The inch (symbol: in) is a unit of length primarily used in the United States customary system of measurement and, to a lesser extent, in the British imperial system. It is defined as exactly 25.4 millimeters (mm), a standard adopted through the 1959 international agreement on the yard and pound between the United States, United Kingdom, Canada, Australia, New Zealand, and South Africa.^[16]^[17] This precise metric equivalent ensures compatibility with the International System of Units (SI) while preserving the inch's role in non-metric contexts, with the National Institute of Standards and Technology (NIST) serving as the authoritative body for its realization in the United States.^[18] Historically, the inch originated from ancient anthropometric measures, such as the approximate width of a human thumb or the length of a digit (finger joint), which evolved into more formalized standards in medieval Europe. By 1324, King Edward II of England decreed that one inch equaled the length of three barleycorns laid end to end, reflecting an effort to standardize variable body-based units like the digit, palm, span, and cubit that had dominated earlier systems.^[19] Over time, the inch became fixed as one-twelfth of a foot, with further refinements in the 19th and 20th centuries tying it to prototypes like the imperial standard yard; however, pre-1959 variations existed, such as the slightly longer "pyramid inch" proposed in some 19th-century theories but never adopted officially.^[20] In contemporary applications, the inch remains integral to industries like manufacturing, aviation, and construction in the U.S., where legal trade requires its use alongside metric equivalents under NIST guidelines. It relates hierarchically as follows: 12 inches equal 1 foot, 36 inches equal 1 yard, and 63,360 inches equal 1 statute mile.^[21] Despite global metrication trends, the inch's definition in exact metric terms has facilitated hybrid usage, such as in international engineering standards, without altering its customary value.^[22]

Geographic and administrative abbreviations

U.S. state abbreviation

The two-letter code "IN" serves as the official United States Postal Service (USPS) abbreviation for the state of Indiana, implemented nationwide on July 1, 1963, alongside the introduction of the ZIP Code system to standardize mail sorting and addressing.^[23] This abbreviation replaced earlier variants, including "Ind." (used from the state's early postal history through the 19th century) and the three-letter "IND" (adopted around 1874 for telegraphic and railway purposes), reflecting a shift toward uniform two-letter formats to reduce errors in automated processing.^[23] Prior to 1963, the USPS generally preferred spelling out state names in full on envelopes but tolerated common abbreviations; the 1963 standardization, recommended by the USPS's Zip Code Advisory Committee, prioritized brevity while avoiding overlap with other states, such as distinguishing Indiana's "IN" from Iowa's "IA."^[23] In practice, "IN" is rendered in uppercase without periods or spaces in official USPS mail formats, as in addresses like "Indianapolis, IN 46201," and extends to federal databases, vehicle registrations, and interstate commerce documents under standards set by the American National Standards Institute (ANSI) and the Federal Information Processing Standards (FIPS).^[24] The code's selection drew from the state's name's initial letters, a convention applied to most states except those with conflicts (e.g., Indiana over Iowa due to alphabetical precedence in some historical lists).^[23] While not legally mandated for non-postal uses, "IN" has become the de facto standard in contexts like ISO 3166-2:US country subdivision codes (US-IN) for international data exchange, ensuring consistency in global trade and statistics.^[24] No changes to "IN" have occurred since 1963, despite periodic reviews of postal standards.^[23]

Organizations and media

Businesses and publications

IN Magazine is a Canadian digital publication that publishes content related to lesbian, gay, bisexual, transgender, queer, intersex, and Two-Spirit communities, with daily online articles and six print issues annually.^[25] inMusic Brands is an American company founded in 2003 that serves as the parent entity for music production and audio equipment brands including Akai Professional, Alesis, and Numark, employing over 300 people and generating annual revenue exceeding $200 million as of 2023.^[26] Disability:IN is a U.S.-based nonprofit organization established in 2001 that collaborates with more than 550 corporations worldwide to promote the inclusion of individuals with disabilities in the workplace through initiatives, research, and benchmarking tools.^[27]

Music and arts

The INmusic festival is an annual open-air rock music festival held in Zagreb, Croatia, founded in 2006 as a one-day event and expanded into a multi-day gathering that has become the country's largest of its kind.^[28] Taking place at Lake Jarun, it attracts tens of thousands of attendees annually and features a mix of international rock, alternative, and indie acts across three main stages.^[29] The festival's growth reflects Croatia's post-2000s emergence as a European music destination, with organizers emphasizing sustainable practices and diverse lineups to draw global audiences.^[30] Past headliners have included Arctic Monkeys in 2007, The Killers and Kings of Leon in subsequent years, Queens of the Stone Age and Nick Cave in 2018, and more recently Jack White and Gorillaz for the 20th anniversary edition planned for 2026.^[31] ^[32] ^[33] British music publication NME has described it as "Europe's best kept festival secret," highlighting its role in showcasing both established and emerging artists amid scenic waterfront settings.^[34] Early editions featured acts like Franz Ferdinand and Morrissey, setting a precedent for high-profile bookings that continue to elevate its status in the regional music scene.^[29]

Other uses

Computing and technology

The abbreviation IN designates the Intelligent Network, a service-independent telecommunications architecture that decouples call control functions from service logic, facilitating the rapid introduction of advanced services such as toll-free calling and virtual private networks without requiring modifications to switching hardware.^[35] Standardized by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) in the Q.1200 series of recommendations during the late 1980s and refined through the 1990s, the IN concept originated from Bellcore (now iconectiv) efforts to enhance public switched telephone network flexibility and has influenced modern service delivery platforms in both fixed and mobile networks.^[35] Core components include the Service Switching Point (SSP) for triggering service requests, Service Control Point (SCP) for hosting logic, and Intelligent Peripheral (IP) for user interactions, enabling centralized management and scalability for operators.^[35] In software development, files with the .in extension serve as templates or input configurations processed by build tools like GNU Autoconf and Automake to generate platform-specific makefiles or scripts.^[36] For instance, Makefile.in provides a generic blueprint that the configure script substitutes with detected system variables, such as paths or compiler flags, producing a customized Makefile for compilation.^[36] This convention, prevalent since the 1990s in open-source projects, promotes portability across Unix-like systems by separating invariant templates from environment-specific details, though it requires tools like m4 for macro expansion.^[37] The "IN" operator appears in multiple programming languages as a membership test or set inclusion mechanism. In SQL, IN filters rows by matching a column value against a comma-separated list or subquery, equivalent to multiple OR conditions for efficiency in queries like SELECT * FROM table WHERE id IN (1, 2, 3).^[38] Python's lowercase "in" keyword similarly checks if an element exists within iterables such as lists, strings, or dictionaries, returning a boolean and supporting iterations in for loops, with time complexity varying by data structure (O(1) average for sets via hashing).^[39] These operators enhance code readability and performance over explicit loops or chained comparisons, though they may underperform on large unsorted collections without indexing.^[39]

Miscellaneous abbreviations

The two-letter country code "IN" designates India under the ISO 3166-1 alpha-2 standard, maintained by the International Organization for Standardization for use in international telecommunication, data exchange, and identification systems such as top-level domain names (.in), currency codes, and vehicle markings. This code facilitates consistent global referencing of the country, which spans 3.287 million square kilometers and had a population of approximately 1.428 billion as of the 2023 estimate. In select technical and archival contexts, "IN" abbreviates "index number," referring to sequential identifiers in catalogs or databases, though this usage lacks universal standardization and varies by system.^[40] Similarly, "IN" has appeared as shorthand for "information network" in older computing documentation describing networked data resources, predating more precise terminology like LAN or WAN.^[40] These applications are niche and often superseded by fuller terms in modern usage to avoid ambiguity with more prevalent meanings like state or unit abbreviations.

References

[1]
Indium | In (Element) - PubChem - NIH
Indium is a chemical element with symbol In and atomic number 49. Classified as a post-transition metal, Indium is a solid at 25°C (room temperature).
[2]
Indium - Element information, properties and uses | Periodic Table
Indium is a soft, malleable metal with a brilliant lustre. The name indium originates from the indigo blue it shows in a spectroscope.
[3]
Chemistry of Indium (Z=49)
Jun 30, 2023 · Indium is the 49th element, abbreviated as In. Discovered in 1863, indium rarely is found as an isolated element. Alloys of indium have low melting points.
[4]
Indium - Periodic Table of Elements: Los Alamos National Laboratory
Atomic Symbol: In, Melting Point: 156.6 °C. Atomic Weight: 114.8, Boiling Point ... Sources. Indium is most frequently associated with zinc materials, and ...Missing: facts reliable<|control11|><|separator|>
[5]
Definition of IN
### Summary of "In" as Preposition and Adverb
[6]
Word Root: in- (Prefix) - Membean
The prefix in, which means “in, on, or not,” appears in numerous English vocabulary words, for example: inject, influx, and insane.
[7]
in-, prefix¹ meanings, etymology and more - Oxford English Dictionary
in- is of multiple origins. Partly a word inherited from Germanic. Partly formed within English, by conversion. Etymons: in adv., in prep.
[8]
Common Latin prefixes | Elementary Latin Class Notes - Fiveable
In- as a locative prefix means "in, into, onto" (ingredior - to enter); In- as a negative prefix means "not, un-" (infelix - unhappy); Variations include il ...
[9]
etymology - Origins of negative prefixes like in-, un-, il-, ir-, dis-, a
Mar 9, 2011 · In general, words take un- when they are of English (Germanic) origin and in- if they come from Latin. (The forms im-, il-, and ir- are ...
[10]
22.1 The Elements of Group 13
Indium (In) and thallium (Tl) were discovered in the 1860s by using spectroscopic techniques, long before methods were available for isolating them.
[11]
Technical data for the element Indium in the Periodic Table
Indium. Symbol, In. Atomic Number, 49. Atomic Weight, 114.818. Density, 7.31 g/cm3. Melting Point, 156.6 °C. Boiling Point, 2072 °C. Thermal properties. Phase ...
[12]
[PDF] Germanium and Indium - USGS Publications Warehouse
Elemental indium is very soft, lustrous, metallic, and malleable, and it has a very low melting point of 156.6 °C. It is a Group 3A element in the periodic ...
[13]
[PDF] Indium - USGS Publications Warehouse
It is a high-volatility, chalcophile element and tends to be associated with sulfide minerals of zinc, whose atom is of a similar size.
[14]
[PDF] Indium - Mineral Commodity Summaries 2024 - USGS.gov
Indium is used in ITO for displays, alloys, solders, and 5G tech. US consumption was 300 tons in 2023. China is a leading producer.
[15]
[PDF] INDIUM - USGS Publications Warehouse
The estimated value of refined indium consumed domestically in 2024, based on the average U.S. warehouse price, was about $85 million. Salient Statistics—United ...
[16]
SI Units – Length | NIST
The new conversion factors were announced in 1959 in Federal Register Notice 59-5442 (June 30, 1959), which states the definition of a standard inch: The value ...
[17]
British-American System of Units - The Physics Hypertextbook
One inch is now defined as exactly 25.4 mm. ... Since the International Yard and Pound Agreement of 1959, the yard has been defined as exactly 914.4 mm.
[18]
[PDF] National Institute of Standards and Technology
Nevertheless, the country still looks to NIST for information on the units of measurement, particularly their definitions and equivalents. The subject of ...
[19]
From the Noggin to the Butt: Quirky Measurement Units Throughout ...
Mar 30, 2022 · On more solid historical ground (but still shaky measurement science ground), King Edward II of England declared in 1324 that the inch was the ...
[20]
[PDF] A Brief HISTORY - National Institute of Standards and Technology
May 9, 2017 · The ancient "digit," "palm," "span," and "cubit" units of length slowly lost preference to the length units "inch,". "foot," and "yard ...
[21]
[PDF] NIST HB 44 2024 Appendix C General Tables of Units of ...
Accurate unit conversions are obtained by selecting an appropriate conversion factor (a ratio which converts one unit of measure into another without changing ...
[22]
[PDF] Units and Systems of Measurement B-1
The National Institute of Standards and Technology (NIST) (formerly the National Bureau of Standards) was established by Act of Congress in 1901 to serve as ...
[23]
State Abbreviations - Who we are - About.usps.com
A brief history of abbreviations used by USPS for states and territories ... Indiana, Ia. Ind. Ind. IND, IN. Iowa, --, Iowa, Iowa, IOWA, IA. Kansas, --, Kans.
[24]
Two–Letter State and Possession Abbreviations - Postal Explorer
Two–Letter State and Possession Abbreviations ; Indiana. IN ; Iowa. IA ; Kansas. KS ; Kentucky. KY ; Louisiana. LA.
[25]
IN Magazine: Canada's Leading 2SLGBTQI+ Digital Publication
IN Magazine is the only national 2SLGBTQI+ publication in Canada. We publish queer-focused content daily on our website and publish our digital publication six ...
[26]
inMusic - Home of the world's premier music industry brands
inMusic is the parent company for a family of premier brands that includes AIR Music Technology, Akai ... in engineering, design, and technology.
[27]
Home | Disability:IN - Your business partner for disability inclusion.
Disability:IN partners with over 550 leading companies to globally advance disability inclusion in business. Are You IN?
[28]
About us | History - INmusic festival
INmusic festival, founded in 2006, is Croatia's biggest open-air rock festival on lake Jarun, called "Europe's best kept festival secret" by NME.Missing: performers | Show results with:performers
[29]
INmusic festival - Zagreb
Two decades of a festival that grew with you, evolved, and became the biggest open-air music event in Croatia. See you at Jarun in 2026! Read more › ...Tickets · Lineup 2025 · The INmusic festival #17... · Festival rules and important...
[30]
INmusic Festival 2025 - Croatia's Biggest Open-Air Event
History of INmusic Festival in Croatia. The journey of the INmusic festival begins in the year 2006 as a modest one-day event. The founders of the festival ...
[31]
INmusic Festival - YOUROPE
Arctic Monkeys, The Cure, The Killers, Kings of Leon, Arcade Fire, Queens of The Stone Age, Nick Cave and the Bad Seeds, Jamiroquai, Florence + The Machine, PJ ...Missing: history performers
[32]
https://www.inmusicfestival.com/en/news/jack-white-set-headline-inmusic-festivals-20th-anniversary
[33]
https://www.inmusicfestival.com/en/news/gorillaz-will-headline-landmark-20th-anniversary-inmusic-festival
[34]
History | INmusic festival
Croatia's biggest open-air rock festival was founded in 2006 and has been growing stronger ever since. INmusic is hailed by NME as the...Missing: performers | Show results with:performers
[35]
Intelligent Network - an overview | ScienceDirect Topics
An Intelligent Network (IN) is a networking standard designed to integrate with various mobile telecom systems, enabling mobile operators to offer a range ...
[36]
IN File Extension - How to open .in files - FileInfo.com
Jun 17, 2020 · An IN file is an input file referenced by GNU Autoconf when building an application. One or more .in or .h.in files may be referenced by an Autoconf script.
[37]
What are .in files? - Unix & Linux Stack Exchange
Jul 25, 2013 · it's just a convention that signifies the given file is for input ; in my experience, these files tend to be a sort of generic template from ...Source files with `*.in` extension - Unix & Linux Stack ExchangeWhich extension to use for text files? (Unix/Linux)More results from unix.stackexchange.com
[38]
SQL IN Operator - W3Schools
The IN operator allows you to specify multiple values in a WHERE clause. The IN operator is a shorthand for multiple OR conditions.SQL BETWEEN Operator · Try it Yourself · Orders
[39]
Python's "in" and "not in" Operators: Check for Membership
Jan 26, 2025 · The in operator in Python is a membership operator used to check if a value is part of a collection. You can write not in in Python to check if ...
[40]
In abbreviation stands for - Smart Define
What does In stand for? ; 69. Internet Name ; 61. Index Number ; 56. Info Network ; 56. Information Network ; 55. information about the National.