What is byzantine eagle flag?

The Byzantine eagle flag, also known as the Tetragrammatic Cross, was the official flag of the Byzantine Empire. It features a black double-headed eagle, symbolizing the power and authority of the empire. The eagle is adorned with a golden crown and is surrounded by four Greek letters, which make up the term IC XC NIKA, meaning "Jesus Christ conquers." The flag was used from the 11th to the 15th century and was a symbol of the Byzantine Empire's military prowess and imperial domination. Today, the Byzantine eagle flag is often used as a symbol of the Orthodox Church and as a cultural symbol in Greece and other countries with strong ties to the Byzantine Empire.