The first ten amendments to the Constitution are collectively called the Bill of Rights.
Congress proposed twelve amendments in 1789, largely in response to Anti-Federalist concerns that the new Constitution did not adequately protect individual liberties. The states ratified ten of those proposed articles on December 15, 1791. Those ten became Amendments One through Ten.
The Bill of Rights protects freedoms and legal guarantees including speech, religion, press, assembly, due process, and protections against unreasonable searches. It also addresses military quartering, criminal trials, bail, punishment, and powers reserved to the states or the people.
James Madison was the main architect of the congressional proposals. The original first and second proposed articles were not ratified at the time; the original second article was eventually ratified in 1992 as the Twenty-seventh Amendment. Thus, the Bill of Rights consists of ten amendments, even though Congress initially sent twelve articles to the states.