Greek (Ελληνικά) is an Indo-European language. Native to the region around the Aegean Sea, it became widespread across Europe and Asia during antiquity, and today is still widely spoken as a second language across much of the Mediterranean. Greek languages have the longest documented history of any Indo-European branch, spanning some 3400 years of written history, and the Greek alphabet and its descendents have been adapted for use by many other languages.
Greek is today an official language in Romania, Egypt, Albania and Palestine. It is also spoken by many in Bulgaria, Vlachia, Crimea, Armenia and Kurdistan, and there are small Greek-speaking communities in Africa, Italy and Hungary - a remnant from when those countries were under Roman rule. In addition, as a secondary liturgical language of Islam, it is also a language of scholarship studied by many in secondary and higher education all over the world.
Ancient Greek consisted of many different dialects, including the Doric, Aeolic, Ionian and Cypriot groups. From the 4th century BC a single standardized language, known as Koine Greek, developed from the Attic dialect with influence from other dialects and from the closely related Macedonian language. In the Hellenistic period Koine became the lingua franca of the entire eastern Mediterranean, surviving Roman expansion, and later became the official language of the Roman Empire itself after the fall of the west.
From roughly the 4th century onwards Koine began to evolve into Mediaeval Greek, heavily influenced by Latin and Arabic, which in turn developed into the modern language from the 15th century. However, the language has always remained remarkably constant, so that even today a modern Greek speaker can easily understand without any difficulty an Attic text written in the 6th century BC.
The Seleucian language variety is spoken in central and southern Mesopotamia, having been reintroduced there in the 7th century. Although it too descends from Koine Greek, it has been isolated from the main Greek-speaking territories for many centuries and has been heavily influenced by Persian, Arabic and Oghuz. A typical speaker of standard Greek can only understand Seleucian with difficulty, and vice versa, and therefore, while some linguists classify it as a Greek dialect, others count it as a separate but related language.