Tau

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Tau uc lc.svg
Greek alphabet
ΑαAlphaΝνNu
ΒβBetaΞξXi
ΓγGammaΟοOmicron
ΔδDeltaΠπPi
ΕεEpsilonΡρRho
ΖζZetaΣσςSigma
ΗηEtaΤτTau
ΘθThetaΥυUpsilon
ΙιIotaΦφPhi
ΚκKappaΧχChi
ΛλLambdaΨψPsi
ΜμMuΩωOmega
History
Archaic local variants
  • Digamma
  • Heta
  • San
  • Koppa
  • Sampi
  • Tsan
Numerals
ϛ (6)
ϟ (90)
ϡ (900)
In other languages
Scientific symbols

 
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Tau uc lc.svg
Greek alphabet
ΑαAlphaΝνNu
ΒβBetaΞξXi
ΓγGammaΟοOmicron
ΔδDeltaΠπPi
ΕεEpsilonΡρRho
ΖζZetaΣσςSigma
ΗηEtaΤτTau
ΘθThetaΥυUpsilon
ΙιIotaΦφPhi
ΚκKappaΧχChi
ΛλLambdaΨψPsi
ΜμMuΩωOmega
History
Archaic local variants
  • Digamma
  • Heta
  • San
  • Koppa
  • Sampi
  • Tsan
Numerals
ϛ (6)
ϟ (90)
ϡ (900)
In other languages
Scientific symbols

Tau (uppercase Τ, lowercase τ; Greek: ταυ [taf]) is the 19th letter of the Greek alphabet. In the system of Greek numerals it has a value of 300.

The name in English is pronounced /t/, but in modern Greek it is [taf]. This is because the pronunciation of the combination of Greek letters αυ has changed from ancient to modern times from one of [au] to either [av] or [af], depending on what follows (see Greek orthography).

Tau was derived from the Phoenician letter taw Phoenician taw.svg. Letters that arose from tau include Roman T and Cyrillic Te (Т, т).

The letter occupies the Unicode slots U+03C4 (lowercase) and U+03A4 (uppercase). In HTML, they can be produced with named entities (τ and Τ), decimal references (τ and Τ), or hexadecimal references (τ and Τ).

Modern usage[edit]

The lower-case letter τ is used as a symbol for:

Biology[edit]

Mathematics[edit]

Physics[edit]

Symbolism[edit]

Character Encodings[edit]

CharacterΤτ
Unicode nameGREEK CAPITAL LETTER TAUGREEK SMALL LETTER TAUCOPTIC CAPITAL LETTER TAUCOPTIC SMALL LETTER TAU
Encodingsdecimalhexdecimalhexdecimalhexdecimalhex
Unicode932U+03A4964U+03C411430U+2CA611431U+2CA7
UTF-8206 164CE A4207 132CF 84226 178 166E2 B2 A6226 178 167E2 B2 A7
Numeric character referenceΤΤττⲦⲦⲧⲧ
Named character referenceΤτ
DOS Greek14793171AB
DOS Greek-2208D0238EE
Windows 1253212D4244F4
TeX\tau
Character𝚻𝛕𝛵𝜏𝜯𝝉
Unicode nameMATHEMATICAL BOLD
CAPITAL TAU
MATHEMATICAL BOLD
SMALL TAU
MATHEMATICAL ITALIC
CAPITAL TAU
MATHEMATICAL ITALIC
SMALL TAU
MATHEMATICAL BOLD ITALIC
CAPITAL TAU
MATHEMATICAL BOLD ITALIC
SMALL TAU
Encodingsdecimalhexdecimalhexdecimalhexdecimalhexdecimalhexdecimalhex
Unicode120507U+1D6BB120533U+1D6D5120565U+1D6F5120591U+1D70F120623U+1D72F120649U+1D749
UTF-8240 157 154 187F0 9D 9A BB240 157 155 149F0 9D 9B 95240 157 155 181F0 9D 9B B5240 157 156 143F0 9D 9C 8F240 157 156 175F0 9D 9C AF240 157 157 137F0 9D 9D 89
UTF-1655349 57019D835 DEBB55349 57045D835 DED555349 57077D835 DEF555349 57103D835 DF0F55349 57135D835 DF2F55349 57161D835 DF49
Numeric character reference𝚻𝚻𝛕𝛕𝛵𝛵𝜏𝜏𝜯𝜯𝝉𝝉
Character𝝩𝞃𝞣𝞽
Unicode nameMATHEMATICAL SANS-SERIF
BOLD CAPITAL TAU
MATHEMATICAL SANS-SERIF
BOLD SMALL TAU
MATHEMATICAL SANS-SERIF
BOLD ITALIC CAPITAL TAU
MATHEMATICAL SANS-SERIF
BOLD ITALIC SMALL TAU
Encodingsdecimalhexdecimalhexdecimalhexdecimalhex
Unicode120681U+1D769120707U+1D783120739U+1D7A3120765U+1D7BD
UTF-8240 157 157 169F0 9D 9D A9240 157 158 131F0 9D 9E 83240 157 158 163F0 9D 9E A3240 157 158 189F0 9D 9E BD
UTF-1655349 57193D835 DF6955349 57219D835 DF8355349 57251D835 DFA355349 57277D835 DFBD
Numeric character reference𝝩𝝩𝞃𝞃𝞣𝞣𝞽𝞽

These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.

References[edit]