What is a Canon

[mparrot]

Got a beginners question for you all. I have A Prayer Book For Orthodox Christians by Holy Transfiguration Monastery. It contains several prayers that it called canons. (Ex. Supplicatory Canon to our Lord Jesus Christ). What are canons? Are they only prayed on certain occasions?

 

[chaldobyzantine]

From OrthodoxWiki:
A canon is a structured hymn used in a number of Orthodox services. It consists of nine odes, sometimes called canticles or songs depending on the translation, based on compositions (also called odes) found in the Bible and, with one exception, the Old Testament.

The canon dates from the 7th century and was either devised or introduced into the Greek language by St. Andrew of Crete, whose penitential Great Canon is still used on certain occasions during Great Lent. It was further developed in the 8th century by Sts. John of Damascus and Cosmas the Hymnographer, and in the 9th century by Sts. Joseph the Hymnographer and Theophanes the Branded.

Over time the canon came to replace the kontakion, a vestigal form of which is still used on several occasions and which has been incorporated into the performance of the canon.