The Patriot Act is a law passed in the United States in 2001, shortly after the September 11 terrorist attacks. Its main purpose is to enhance national security by giving law enforcement agencies more tools to prevent and investigate terrorism. This includes expanded surveillance capabilities and the ability to share information between agencies. The act has been controversial, as some people believe it infringes on civil liberties and privacy rights. Critics argue that certain provisions allow for excessive government surveillance, while supporters claim it is necessary for protecting the country from future threats.