Classical 
  Greek (sometimes referred to as Attic Greek), which was the dominant dialect 
  of classical Greek) is the form of Greek used in the period commonly referred 
  to as the classical period or the Golden Age of Greek culture. It is the form 
  of Greek spoken before the Greeks are unified into the powerful Mediterranean 
  empire under Philip of Macedonia and Alexander, his son. That empire survived 
  for about three hundred years), and it took seriously a task of spreading Greek 
  culture widely throughout the Mediterranean. The language used in this was Greek, 
  but it was tailored (and simplified) for use by non-native speakers. This came 
  to be called the koine and the period of its use was called the Hellenistic 
  period. At times during the Hellenistic period, authors tried to mimic the more 
  literary classical Greek.