The orthography of the modern Greek language was standardised in 1976 and simplified the diacritics in 1982. There are relatively few differences between the orthography of Ancient Greek and Modern Greek.
Some time prior to that, one early form of Greek, Mycenaean, was written in Linear B, although there was a lapse of several centuries (the Greek Dark Ages) between the time Mycenaean stopped being written and the time when the Greek alphabet came into use.
Greek orthography has used a variety of diacritics starting in the Hellenistic period. The more complex polytonic orthography (Greek: πολυτονικὸ σύστημα γραφῆς, romanized: polytonikò sýstīma grafī̂s), which includes five diacritics, notates Ancient Greek phonology. The simpler monotonic orthography (Greek: μονοτονικό σύστημα γραφής, romanized: monotonikó sýstīma grafī́s), introduced in 1982, corresponds to Modern Greek phonology, and requires only two diacritics.
Polytonic orthography (from Ancient Greek πολύς (polýs) 'much, many' and τόνος (tónos) 'accent') is the standard system for Ancient Greek and Medieval Greek and includes:
Tau (/ˈtaʊ, ˈtɔː, ˈtɒ/ ; uppercase Τ, lowercase τ or τ; Greek: ταυ [taf]) is the nineteenth letter of the Greek alphabet, representing the voiceless dental or alveolar plosive IPA: [t]. In the system of Greek numerals, it has a value of 300.
The name in English is pronounced /taʊ/ or /tɔː/, but in Greek it is [taf]. 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).