The Cambridge Union Society, also known as the Cambridge Union, is a debating and free speech society in Cambridge, England, and the largest society in the University of Cambridge. The society was founded in 1815 and is the oldest continuously running debating society in the world. Additionally, the Cambridge Union has served as a model for the foundation of similar societies at several other prominent universities, including the Oxford Union and the Yale Political Union. The Union is a private society with membership open to all students of Cambridge University and Anglia Ruskin University. The Cambridge Union is a registered charity and is completely separate from the Cambridge University Students' Union.

Debate is a process that involves formal discourse, discussion, and oral addresses on a particular topic or collection of topics, often with a moderator and an audience. In a debate, arguments are put forward for common opposing viewpoints. Debates have historically occurred in public meetings, academic institutions, debate halls, coffeehouses, competitions, and legislative assemblies. Debates have also been conducted for educational and recreational purposes, usually associated with educational establishments and debating societies. These debates emphasized logical consistency, factual accuracy, and emotional appeal to an audience. Modern forms of competitive debate also include rules for participants to discuss and decide upon the framework of the debates.