Tau

; Greek: ταυ [taf]) is the nineteenth letter of the Greek alphabet, representing the voiceless dental or alveolar plosive IPA: [t].

The name in English is pronounced /taʊ/ or /tɔː/,[2] but in Greek it is [taf].

[3][4] This is because the pronunciation of the combination of Greek letters αυ can have the pronunciation of either [ai], [av] or [af], depending on what follows and if a diaeresis is present on the second vowel (see Greek orthography).

Tau was derived from the Phoenician letter taw (𐤕).

[5] Letters that arose from tau include Roman T and Cyrillic Te (Т, т).