The Patriot Act is a law enacted in the United States in response to the September 11, 2001 terrorist attacks. Its primary aim is to enhance national security by expanding the government's surveillance and investigative powers. This includes measures such as allowing law enforcement to monitor communications and access personal records without a warrant in certain situations. The act has been controversial, as critics argue it infringes on civil liberties and privacy rights. Supporters, however, believe it is essential for preventing terrorism and protecting the nation. The Patriot Act has undergone several revisions and renewals since its initial passage.