This document provides a summary of precedent as a source of law, including ratio decidendi and obiter dictum. It discusses that precedent refers to the reasoning behind a judge's decision that establishes a legal principle that must be followed by lower courts. There are binding precedents from higher courts that must be followed, and persuasive precedents that provide guidance but do not have to be followed. Ratio decidendi refers to the legal principles on which a court's decision is based, while obiter dictum refers to additional non-binding remarks made by the judge.