The American Bill of Rights is significant because it guarantees individual liberties and limits governmental power. Ratified in 1791, it comprises the first ten amendments to the U.S. Constitution, protecting fundamental rights like freedom of speech, religion, assembly, and the right to bear arms. The Bill of Rights was essential in addressing Anti-Federalist concerns during the ratification debates and helped to ensure that there would be legal protections for citizens against potential government overreach. Its establishment laid the foundation for civil rights movements and continues to influence American law and society today.