ASCII Character ΗGreek capital letter Eta
Eta /ˈiːtə, ˈeɪtə/ (uppercase Η, lowercase η; Ancient Greek: ἦτα ē̂ta [ɛ̂ːta] or Greek: ήτα ita [ˈita]) is the seventh letter of the Greek alphabet, representing the close front unrounded vowel IPA: [i]. In the ancient Attic number system (Herodianic or acrophonic numbers), the number 100 was represented by "Η", because it was the initial of ΗΕΚΑΤΟΝ, the ancient spelling of ἑκατόν = "one hundred". In the later system of (Classical) Greek numerals eta represents 8. Eta was derived from the Phoenician letter heth Phoenician heth.svg. Letters that arose from eta include the Latin H and the Cyrillic letter И and Й. In information theory the uppercase Greek letter Η is used to represent the concept of entropy of a discrete random variable.