Tan
Tan is a pale tone of brown, specifically a light yellowish-brown hue derived from the color imparted to leather during the tanning process using materials like oak bark.[1][2] The standard web color representation of tan uses the hexadecimal code #D2B48C, positioning it within the spectrum of neutral earth tones akin to beige and tawny but distinguished by its subtle warmth and association with natural materials.[2] In practical applications, tan functions as a versatile neutral in fashion, interior design, and military attire—such as khaki uniforms—due to its camouflage properties in arid environments and its understated aesthetic that complements a range of palettes without dominating.[3][4] While variations like sandy tan or Tuscan tan exist for nuanced shades, the core defining characteristic remains its origin in the chemical transformation of hides, yielding a durable, muted brown that reflects practical utility over vibrancy.[5]Mathematics
Trigonometric tangent
The trigonometric tangent function, denoted \tan \theta, is defined for an acute angle \theta in a right triangle as the ratio of the length of the side opposite \theta to the length of the side adjacent to \theta.[6] Equivalently, \tan \theta = \frac{\sin \theta}{\cos \theta}, where \sin \theta and \cos \theta are the sine and cosine functions, respectively.[7] This ratio extends to the unit circle, where for a point (\cos \theta, \sin \theta), \tan \theta equals the y-coordinate divided by the x-coordinate, excluding points where \cos \theta = 0.[8] The function is periodic with period \pi, satisfying \tan(\theta + \pi) = \tan \theta for all \theta in its domain, and exhibits vertical asymptotes at \theta = \frac{\pi}{2} + k\pi for integers k, where the function approaches positive or negative infinity.[7] It is an odd function, with \tan(-\theta) = -\tan \theta, and its range is all real numbers. The derivative of \tan x is \sec^2 x = 1 + \tan^2 x, a fundamental identity linking it to other trigonometric functions.[9] The term "tangent" derives from the Latin tangens, meaning "touching," reflecting its geometric origin in the tangent line from the origin to a circle, whose length equals the value of the function for the angle subtended at the center.[10] The symbol \tan was introduced by Thomas Fincke in his 1583 work Geometria rotundi, though tangent tables appeared earlier in works by Regiomontanus in the 15th century, building on Ptolemy's chord tables from the 2nd century CE, which indirectly computed tangent values via shadow lengths in astronomy.[11][12] In mathematics, the tangent function solves for unknown sides or angles in right triangles, as \tan \theta = \frac{\text{opposite}}{\text{adjacent}} directly yields ratios without hypotenuse involvement.[6] It models slopes in calculus, appears in Fourier series for periodic phenomena, and features in complex analysis via the identity \tan z = -i \frac{e^{iz} - e^{-iz}}{e^{iz} + e^{-iz}}.[9] Key identities include the Pythagorean \tan^2 \theta + 1 = \sec^2 \theta and the double-angle formula \tan 2\theta = \frac{2 \tan \theta}{1 - \tan^2 \theta}, enabling reductions in trigonometric equations.[7]Physical sciences and biology
Tan (color)
Tan is a pale tan-brown color that evokes the hue of tanned leather, characterized by its warm, neutral tone positioned between beige and light brown on the color spectrum.[13] In digital standards, the web color tan is defined by the hexadecimal code #D2B48C, with RGB values of 210, 180, 140, and CMYK values of 0%, 14%, 33%, 18%.[5] [14] This specification ensures consistency in web design and CSS applications, where it serves as a versatile base for earthy palettes.[3] The term "tan" as a color name derives from "tannum," referring to oak bark used in the traditional leather tanning process, which imparts a similar light brown shade to hides.[15] The first documented use of "tan" specifically as an English color name dates to 1590, though related terms like "tawny" described comparable shades in earlier centuries.[16] Prior to modern standardization, tan's appearance varied based on natural tanning methods, but its adoption in pigments and dyes reflected practical associations with durable, sun-faded materials.[17] In practical applications, tan functions as a subdued neutral in fashion, interior design, and graphic arts, often paired with deeper browns or greens to convey stability and approachability without overwhelming vibrancy.[18] Its low saturation—approximately 33% yellow dominance in RGB models—makes it suitable for backgrounds or accents in user interfaces, promoting readability and a sense of grounded warmth.[19] While not formally codified in systems like Pantone under a single "tan" swatch, analogous shades appear in professional color libraries for matching natural tones in printing and textiles.[20]Leather tanning
Leather tanning is the process of chemically treating raw animal hides and skins to convert the unstable collagen proteins into a stable, durable material known as leather, which resists biological decay and environmental degradation.[21] This transformation occurs through cross-linking of protein fibers with tanning agents, preventing putrefaction that would otherwise occur within days of an animal's death.[22] Evidence of tanning dates back to at least 7000 BCE, with archaeological finds from sites like Mehrgarh indicating early use of plant-based methods, though primitive softening of hides using fats or brains predates formalized tanning by tens of thousands of years.[23] The traditional process begins with beamhouse operations: hides are preserved with salt to inhibit bacterial growth, then soaked in water to rehydrate and remove salt, followed by liming in a calcium hydroxide solution to loosen hair and flesh, which are then mechanically removed via scudding.[21] Deliming with ammonium sulfate neutralizes the alkaline pH, and pickling in sulfuric acid and salt prepares the hides for tanning by contracting the fibers. The core tanning step involves immersion in solutions of tanning agents, after which neutralization, fatliquoring for lubrication, and drying produce finished leather.[22] Vegetable tanning, the oldest method still in use, employs polyphenolic tannins extracted from tree barks (e.g., oak, chestnut) or leaves, requiring 4–12 weeks of sequential immersion in strengthening liquors to achieve deep penetration and firm, water-resistant leather suitable for saddles and bookbinding.[24] This organic process yields leather that ages with a patina but is labor-intensive and produces bulkier hides. In contrast, chrome tanning—introduced in 1858 by German chemist Auguste Schultz using chromium(III) sulfate—completes in 24 hours, resulting in softer, more supple, stretchable leather that constitutes over 80% of global production due to its efficiency, lower cost, and suitability for garments and upholstery.[22] [23] Chrome-tanned leather exhibits better heat and water resistance but requires careful wastewater management to mitigate chromium pollution risks.[25] Alternative methods include aldehyde tanning with glutaraldehyde for medical-grade leather and synthetic tanning with phenolic or naphthalene compounds, often combined with chrome for hybrid properties, though these represent minor shares of production.[21] Modern innovations focus on reducing chemical use and effluent, such as enzyme-assisted unhairing to minimize sulfide waste, driven by regulations like the European Union's REACH framework since 2007.[22] Despite chrome's dominance, vegetable tanning persists for artisanal and eco-premium markets, with annual global leather output exceeding 20 billion square feet as of 2023.[23]Sun tanning
Sun tanning is the darkening of the skin resulting from exposure to ultraviolet (UV) radiation, primarily from sunlight, which stimulates melanocytes in the epidermis to produce melanin pigment as a protective response against further UV damage. This process, known as melanogenesis, involves two main types: immediate pigment darkening, triggered by UVA rays oxidizing existing melanin within minutes, and delayed tanning, induced by UVB rays that damage DNA in keratinocytes, prompting the release of signaling molecules like alpha-melanocyte-stimulating hormone (α-MSH) to increase eumelanin synthesis over 48-72 hours.[26][27] The resulting tan provides limited photoprotection, equivalent to an SPF of about 2-4, insufficient to prevent burns or long-term harm.[28] Physiologically, UV exposure elevates reactive oxygen species and DNA damage in skin cells, activating repair pathways that prioritize immediate survival over pigmentation, with tanning as a secondary adaptation. While UVB facilitates cutaneous vitamin D3 synthesis by converting 7-dehydrocholesterol to previtamin D3 in the epidermis—potentially yielding sufficient levels from brief midday exposure—excessive tanning does not reliably optimize this without risking overdose or deficiency in varied skin types and latitudes.[29][30] However, the primary health consequences are adverse: UV-induced tanning accelerates photoaging through collagen degradation and elastosis, and substantially elevates skin cancer risk, with even moderate exposure linked to non-melanoma cancers (over 5.4 million U.S. cases annually) and melanoma. Indoor tanning before age 35 increases melanoma risk by 59-75%, as devices emit concentrated UVA that penetrates deeper without proportional vitamin D benefits.[31][32][33] Culturally, sun tanning shifted from a marker of manual labor—despised by elites favoring pale skin in ancient and pre-20th-century societies—to a symbol of leisure after French designer Coco Chanel's 1923 Riviera voyage popularized a tanned complexion as affluent and healthy, reversing prior aesthetics by the 1930s. This trend persists despite evidence that any tan signifies cumulative DNA damage, not health, with no "safe" threshold for UV exposure.[34][35] Self-tanning alternatives using dihydroxyacetone (DHA) mimic color without UV risks but offer no photoprotection.[36]Surname
Etymology and distribution
The surname Tan primarily originates from Chinese linguistic and historical roots, representing the romanization of several distinct hanzi characters. One key etymology traces to 譚 (Tán in Mandarin pinyin), derived from the name of the ancient State of Tan, located in present-day Shandong Province during the Zhou dynasty (c. 1046–256 BCE), where inhabitants adopted the place name as their clan identifier following conquests by the Yan state.[37] [38] Another prevalent form stems from dialectal pronunciations of 陳 (Chén in Mandarin), particularly in Hokkien (Minnan) spoken in Fujian Province, where it is rendered as Tan; this character traces to the ancient state of Chen (c. 11th century BCE) in Henan Province, with descendants adopting it as a surname after its annexation by Chu in 479 BCE.[39] Less commonly, Tan romanizes characters like 檀 (Tán, referring to sandalwood) or 談 (tán, meaning "to discuss"), but these are rarer and often regionally specific.[40] In non-Chinese contexts, such as Vietnam, Tan may derive from Sino-Vietnamese readings of similar characters like Tân (new or fresh), though these are secondary to Chinese influences via migration and Sinicization.[41] Globally, Tan ranks as the 49th most common surname, borne by approximately 10.1 million individuals as of recent estimates, equivalent to about 1 in 727 people worldwide, with over 98% incidence in Asia.[39] Its highest concentrations occur in China (particularly Fujian and Guangdong provinces, sources of much overseas migration over the past four centuries), followed by Indonesia (over 1.5 million bearers, largely from Chinese diaspora communities), Malaysia, Singapore, Vietnam, and the Philippines, reflecting 19th- and 20th-century labor migrations and trade networks from southern China.[37] [39] In the United States, Tan bearers number around 20,000 as of 2020 census data proxies, with 92% identifying as Asian or Pacific Islander ancestry, predominantly Chinese.[42] Diaspora patterns show Tan comprising a significant portion of ethnic Chinese populations in Southeast Asia, where Hokkien-influenced romanizations dominate, though mainland Chinese statistics often aggregate under Chén for 陳, masking the full Tan-equivalent prevalence exceeding 70 million for that lineage alone.[39] Outside Asia, frequencies remain low, with negligible non-Asian origins like potential English occupational ties to tanning (unsubstantiated in primary records) or Dutch variants.Notable individuals
Amy Tan (born February 19, 1952) is an American novelist whose debut work, The Joy Luck Club (1989), explores mother-daughter relationships among Chinese-American families and sold over 6 million copies worldwide; it was adapted into a feature film in 1993.[43] Her parents immigrated from China during the civil war of the 1940s, influencing her themes of cultural identity and family dynamics across subsequent novels like The Kitchen God's Wife (1991) and The Hundred Secret Senses (1995).[44] Tan Dun (born August 18, 1957) is a Chinese-born composer renowned for blending Eastern and Western musical traditions, earning the Academy Award for Best Original Score for Crouching Tiger, Hidden Dragon (2000) in 2001, as well as a Grammy Award for the film's soundtrack.[45] His oeuvre includes operas such as Marco Polo (1996), which won the Grawemeyer Award for Music Composition, and multimedia works incorporating water, paper, and stone as percussion instruments, performed by major orchestras globally.[46] Tony Tan Keng Yam (born February 7, 1940) served as the seventh President of Singapore from September 1, 2011, to September 1, 2017, following his election on August 27, 2011, with 35.2% of the vote in a four-way contest.[47] Prior to the presidency, he held roles as Deputy Prime Minister (1995–2005), Minister for Defence (1995–2003), and Chairman of the Government of Singapore Investment Corporation (GIC), leveraging his background in banking and physics from the University of Adelaide.[48] Tan Cheng Bock (born April 26, 1940) is a Singaporean physician and politician who represented Ayer Rajah as a People's Action Party Member of Parliament from December 1980 to 2006, known for his independent-minded contributions in parliament.[49] He founded the Progress Singapore Party in 2019, serving as its chairman until announcing his retirement from electoral politics on May 10, 2025, while remaining involved in party advisory roles.[50] [51] Tan Sitong (October 10, 1865–September 28, 1898) was a late-Qing Chinese reformist thinker and official who advocated radical modernization, including abolishing the imperial examination system and establishing schools and factories, during the Hundred Days' Reform of 1898.[52] As one of the "Six Gentlemen," he refused to flee arrest and was executed by beheading in Beijing after the reform's failure, becoming a martyr symbolizing resistance to conservative forces.[53] Tan Kah Kee (October 21, 1874–August 12, 1961) was a Fujian-born entrepreneur and philanthropist who amassed wealth in Southeast Asia through rubber plantations and enterprises before donating substantially to education, founding Xiamen University on April 26, 1921, with initial funding of 1 million silver dollars.[54] His contributions extended to over 130 schools in Singapore, Malaysia, and China, including the establishment of five primary and secondary schools in Singapore by 1918, reflecting his commitment to Chinese community upliftment amid colonial-era challenges.[55][56]Places
In China
Tanmen Town (潭门镇) is a coastal fishing community in Qionghai City, Hainan Province, serving as a key port for operations in the South China Sea. Local fishermen from Tanmen have historically ventured into disputed waters, including the Spratly Islands, asserting territorial claims through sustained presence since at least the mid-20th century. The town features natural deep-water ports like Longwan Port and Tanmen Central Fishing Port, supporting a fleet that contributes significantly to China's maritime activities in the region.[57][58][59] Tanzhou Town (坦洲镇) lies at the southern tip of Zhongshan City in Guangdong Province, bordering Zhuhai and the Pearl River estuary. Covering approximately 80 square kilometers with a population exceeding 200,000 as of recent estimates, it functions as an industrial hub focused on manufacturing, including furniture and electronics, while preserving local culinary traditions like wonton noodles and saltwater folk songs. The town's economy benefits from proximity to Hong Kong and Macao, facilitating trade and tourism.[60][61] Tan Village (谭村) in Wuxi City, Jiangsu Province, exemplifies rural revitalization efforts, with upgrades to housing, cafeterias for seniors, and ecological preservation transforming it from traditional agriculture to a model of sustainable development. Recent initiatives include community dining facilities opened around 2024 to support elderly residents amid urbanization trends.[62][63] Smaller settlements, such as Tan Village in Xunyi County, Shaanxi Province, represent typical administrative villages (村委会) in inland areas, primarily agricultural with historical roots traceable to local clan migrations.[64]In Vietnam
Tân An is the capital city of Long An Province in the Mekong Delta region of southern Vietnam.[65] Covering an area of 81.49 km², it had a population of 145,120 as of the 2019 census. The city serves as an administrative and economic hub for the province, facilitating connections between Ho Chi Minh City and the broader delta area.[66] Tân Bình District is an urban district in Ho Chi Minh City, spanning approximately 20.4 km² with a population exceeding 500,000 residents.[67] It hosts Tan Son Nhat International Airport, Vietnam's busiest aviation gateway, handling millions of passengers annually and supporting the city's logistics and tourism sectors.[68] The district features a mix of commercial zones, markets, and residential areas, contributing to Ho Chi Minh City's northwestern expansion.[69] Bình Tân District, another urban district in Ho Chi Minh City, covers 52 km² and recorded a population of 784,173 in 2019, making it one of the city's most populous areas.[70] Characterized by high migrant worker communities and industrial growth, it emerged from the merger of former areas like Bình Hưng Hòa and Tân Tạo, fostering rapid urbanization and labor-intensive enterprises.[71] The district's density reflects broader trends in southern Vietnam's economic migration patterns.[70]In other locations
Tan-Tan is a city in southwestern Morocco, serving as the capital of Tan-Tan Province within the Guelmim-Oued Noun region. Located approximately 25 kilometers inland from the Atlantic coast amid the northwestern Sahara Desert, it acts as a key administrative and trade hub for Saharan nomadic communities. The city's population was estimated at 61,924 in 2025.[72] In India, Tan is a small village in Kuru tehsil, Lohardaga district, Jharkhand state. As per the 2011 census, it had a population of 885, comprising 417 males and 468 females, with a literacy rate of 61.1%.[73] The village lies about 9 kilometers from the sub-district headquarters of Kuru.[74]Organizations and finance
Businesses and organizations
Palm Beach Tan, a prominent chain in the indoor tanning sector, operates numerous salons across the United States and underwent a rebranding to Palm Beach Beauty and Tan in 2025 to broaden its appeal beyond traditional UV tanning services.[75] TanCo maintains a network of tanning facilities emphasizing clean environments, skincare products, and customer service, with multiple locations serving UV and sunless tanning needs.[76] Tanco, founded in 1994, has developed into a regional leader in the tanning industry, offering UV tanning alongside complementary services from its salons in Missouri.[77] The American Suntanning Association (ASA), established to represent professional sunbed operators, promotes education on UV exposure and supports small businesses in the sector as integral community enterprises.[78] In the leather sector, Tan Holdings operates in New York, handling tanning-related distribution and services tied to material processing.[79] These entities reflect the commercial landscape of tanning processes, where businesses prioritize safety standards and market adaptation amid health regulatory scrutiny.[80]Financial instruments
A tax anticipation note (TAN) is a short-term debt security issued by state, county, or local governments to finance immediate operational needs or infrastructure projects in advance of expected tax revenues, such as property taxes.[81] These instruments typically have maturities of one year or less, providing temporary liquidity until fiscal inflows materialize, and are repaid directly from the anticipated tax collections.[82] Interest payments on TANs are exempt from federal income taxation, though subject to state and local taxes depending on the issuer's jurisdiction, which enhances their appeal to tax-sensitive investors seeking low-risk, short-duration fixed-income options.[81] Governments issue TANs during periods of cash shortfall, such as mid-fiscal year delays in tax remittances, ensuring continuity of public services without resorting to longer-term borrowing.[83] The ticker symbol TAN also designates the Invesco Solar ETF, an exchange-traded fund launched on June 19, 2008, that provides exposure to global companies engaged in solar energy production, distribution, and related technologies.[84] The ETF tracks the MAC Global Solar Energy Index, a market-capitalization-weighted benchmark of solar-focused firms, with at least 90% of its assets invested in index constituents or American Depositary Receipts (ADRs) of such companies.[84] As of October 22, 2025, the fund held approximately $921.1 million in assets under management, with a net asset value around $47.95 per share, reflecting volatility tied to renewable energy sector trends and policy shifts.[85] Holdings are concentrated in areas like photovoltaic manufacturing and solar power generation, excluding broader clean energy segments to maintain thematic purity.[86] The ETF's expense ratio stands at 0.67%, positioning it as a leveraged vehicle for investors betting on solar industry growth amid global decarbonization efforts.[84]Arts and entertainment
Media and fiction
Amy Tan, an American author of Chinese descent, achieved prominence with her debut novel The Joy Luck Club (1989), which interweaves stories of four Chinese immigrant mothers and their American-born daughters, drawing on themes of cultural identity and generational conflict. The book sold over 6 million copies worldwide and was adapted into a feature film in 1993, directed by Wayne Wang and starring Ming-Na Wen, which grossed $33 million at the box office and earned critical acclaim for its portrayal of diaspora experiences. Tan's subsequent novels, such as The Kitchen God's Wife (1991) and The Bonesetter's Daughter (2001), similarly explore familial legacies and historical traumas rooted in Chinese heritage. Shaun Tan, an Australian writer and illustrator, is known for speculative fiction and picture books that address alienation and migration, including the wordless graphic novel The Arrival (2006), which depicts an immigrant's surreal journey to a fantastical city and won the Astrid Lindgren Memorial Award in 2011. His works, such as The Lost Thing (2000)—adapted into an Academy Award-winning animated short in 2010—employ visual storytelling to evoke emotional responses to otherness without explicit narrative prose. Tan Twan Eng's novels, set against Malaysian and Southeast Asian backdrops, include The Gift of Rain (2007), shortlisted for the Man Booker Prize, which examines interracial friendships and wartime betrayals through the lens of a half-Chinese protagonist. His The Garden of Evening Mists (2012) won the Man Asian Literary Prize and was adapted into a 2024 film, focusing on memory, trauma, and Japanese internment in post-WWII Malaya. In film, the character Mr. Tan appears as a minor antagonist in the James Bond movie Licence to Kill (1989), portrayed by Anthony Starke as an Asian drug lord collaborating with the primary villain Franz Sanchez in a cocaine smuggling operation. Fictional elements named Tan also feature in anime and manga, such as the elixir "Tan" in Hell's Paradise: Jigokuraku (2018–present), a life-extending substance central to the plot involving immortal beings harvesting human energy.[87] Lisa See's historical novel Lady Tan's Circle of Women (2023) fictionalizes the life of Tan Yunxian, a 15th-century Chinese female physician, emphasizing women's networks in Ming Dynasty society amid Confucian restrictions.Music
Tan Dun (born August 18, 1957) is a Chinese-born American composer and conductor recognized for fusing Western classical forms with Chinese musical elements, including percussion, opera, and multimedia techniques.[46] His works, such as the opera Marco Polo (1996), which earned the Grawemeyer Award for Music Composition in 1998, exemplify this synthesis through innovative orchestration and cultural integration.[88] Tan has conducted major orchestras worldwide, including the London Symphony Orchestra and Philadelphia Orchestra, and holds positions such as Principal Guest Conductor of the Mariinsky Theatre in St. Petersburg.[46] Tan's film score for Crouching Tiger, Hidden Dragon (2000) won the Academy Award for Best Original Score and a Grammy Award for Best Score Soundtrack Album, highlighting his ability to blend erhu, pipa, and cello with Hollywood orchestration.[89] Other honors include the Shostakovich Award in Music and Japan's Praemium Imperiale, reflecting his global influence in contemporary music.[88] He served as dean of the Bard College Conservatory of Music and is a UNESCO Goodwill Ambassador.[90] Less prominent figures include Tan Onwimon, a Thailand-born composer based in Los Angeles specializing in media scoring for film, theater, and games.[91] Chrysanthe Tan, a Cambodian-Greek-American violinist and singer-songwriter, composes works drawing from diverse cultural influences.[92] In popular music, "Atom Tan" is a 1982 track by the British punk band The Clash from their album Combat Rock.[93]Other uses
Acronyms
- Tax Deduction and Collection Account Number (TAN): A unique 10-digit alphanumeric identifier issued by the Income Tax Department of India to entities responsible for deducting or collecting tax at source, required for filing TDS/TCS returns and issuing certificates.
- Transaction Authentication Number (TAN): A one-time password or code used in online banking systems, particularly in Europe such as Germany's Transaktionsnummer, to authorize financial transactions and prevent unauthorized access.
- Total Acid Number (TAN): A measure of the acidity level in petroleum products, lubricants, or crude oil, expressed in milligrams of potassium hydroxide per gram of sample, used to assess degradation or additive depletion.
- Tax Account Number (TAN): In various jurisdictions, a registration number for tax-related activities, such as in Germany for VAT purposes or in some U.S. contexts for specific tax accounts..html)
- Temporary Authorization Number (TAN): A short-term code or password with an expiration date, often used in secure systems for provisional access, such as in military or IT environments.[94]