Koine is a common form of the Greek language that emerged around the 4th century BCE and was widely spoken throughout the Hellenistic and Roman periods. It served as a lingua franca, allowing people from different regions to communicate effectively. This simplified version of Greek was used in various contexts, including trade, literature, and administration. Notably, the New Testament of the Christian Bible was written in Koine, making it significant for both historical and religious studies. Its influence can still be seen in modern Greek and other languages today.