Congress originally proposed 12 amendments with the 1789 Bill of Rights.
James Madison introduced the proposals in the House of Representatives on June 8, 1789. Congress approved 12 articles and sent them to the states for ratification. The first two proposals did not receive approval from enough states at that time, so only Articles 3 through 12 became the first ten amendments in 1791.
The original First Amendment proposal concerned the size of the House of Representatives. The original Second Amendment dealt with congressional pay and was not ratified during the founding era. It was eventually ratified in 1992 as the Twenty-Seventh Amendment.
This history explains why the Bill of Rights contains 10 amendments even though Congress proposed 12. The phrase “Bill of Rights” commonly refers to the first ten amendments, which protect freedoms such as religion, speech, press, assembly, due process, and protection from unreasonable searches.