I get asked this question often, mostly because I show my credentials as a Canon Lawyer on all my stationery, business cards, web site, you get the picture. So here is about as formal as I will get on this blog.
Canon Law describes the regulations that govern the Roman Catholic Church. There are other codes of Canon Law, like the separate Code for Eastern Churches, and the laws and regulations of the Anglican Communion, Presbyterian and Reformed Churches, Lutheranism and the United Methodist Church to name the ones most generally known.. The most recent Code of Canon Law for the Roman Catholic Church was promulgated in 1983. There had been one prior, modern codification and that was published in 1917. Imagine not updating your laws for 66 years.
Most Civil Codes of Law have numerous volumes and thousands of pages and get updated in some way, almost daily. The Civil Codes look really nice on a book shelf and give a lot of ambiance as back drop for lawyer interviews for social media. But the Code of Canon Law for the Roman Catholic Church is a single volume broken down into seven, self-designated “books”, with 1752 canons. The word “canon” comes historically from the name of a reed that grows straight enough that it can be used as a measuring stick. In the Code, canon refers to a standard or norm. For the Roman Catholic Church, the major laws are found in the Code of Canon Law. For this reason an understanding of the Canons is an important part of being Catholic.