The United States Bill of Rights consists of 10 amendments to the Constitution. They were ratified on December 15, 1791.
The Bill of Rights was developed after critics of the proposed Constitution argued that it needed explicit protections for individual liberties. James Madison introduced a group of amendments in the First Congress, drawing on state declarations of rights and earlier English legal traditions.
Congress originally proposed 12 amendments in 1789. The first two proposals were not ratified at that time. The remaining ten became the Bill of Rights, covering freedoms and legal protections such as religion, speech, press, assembly, due process, and protection from unreasonable searches.
A frequent misunderstanding is that the Bill of Rights was written as a separate constitution. It is part of the Constitution itself. The original second proposed article was eventually ratified in 1992 as the Twenty-seventh Amendment, while the original first article still has not become part of the Constitution.