Ancient Greek grammar is morphologically complex and preserves several features of Proto-Indo-European morphology. Nouns, adjectives, pronouns, articles, numerals and especially verbs are all highly inflected. A complication of Greek grammar is that different Greek authors wrote in different dialects, all of which have slightly different grammatical forms (see Ancient Greek dialects). For example, the history of Herodotus and medical works of Hippocrates are written in Ionic, the poems of Sappho in Aeolic, and the odes of Pindar in Doric; the poems of Homer are written in a mixed dialect, mostly Ionic, with many archaic and poetic forms. The grammar of Koine Greek (the Greek lingua franca spoken in the Hellenistic and later periods) also differs slightly from classical Greek. This article primarily discusses the morphology and syntax of Attic Greek, that is the Greek spoken at Athens in the century from 430 BC to 330 BC, as exemplified in the historical works of Thucydides and Xenophon, the comedies of Aristophanes, the philosophical dialogues of Plato, and the speeches of Lysias and Demosthenes. Source: Wikipedia (en)