Heta

Heta is a conventional name for the historical Greek alphabet letter Eta (Η) and several of its variants, when used in their original function of denoting the consonant /h/.

In dialects that still had the /h/ sound as part of their phonological systems, including early Athens, the same letter continued to be used in its consonantal function.

In the southern Italian colonies of Heracleia and Tarentum, a new innovative shape for /h/ was invented, consisting of a single vertical stem and a rightward-pointing horizontal bar, like a half H ().

From this sign, later scholars developed the rough breathing or spiritus asper, which brought back the marking of the old /h/ sound into the standardized post-classical (polytonic) orthography of Greek in the form of a diacritic.

Διὰ τί δὲ πάντων τῶν φωνηέντων ψιλουμένων, μόνου τοῦ υ φυσικὴν δασεῖαν ἔχοντος, τὸ ἧτα δασύνεται; Ὅτι πάλαι τὸ Η χαρακτὴρ ἦν τῆς δασείας· τοῦ Η τοίνυν χαρακτῆρα τῆς δασείας ἔχοντος, εὐλόγως καὶ τὸ ὄνομα αὐτοῦ δασύνεται· καὶ γὰρ ἄτοπον ἦν ἄλλοις χορηγοῦν τὴν πρόσπνευσιν τῆς δασείας αὐτὸ ταύτης στερεῖσθαι.

The Unicode standard of computer encoding introduced code points for a tack-shaped "Greek letter Heta" designed for this usage in its version 5.1 of April 2008.