The United States Postal Inspection Service, also known as USPSIS, is the law enforcement arm of the United States Postal Service. The agency is responsible for investigating and securing the U.S. mail against fraud, theft, and other criminal activities. Other synonyms that can be used for the USPSIS include the U.S. Postal Inspection Service, the Postal Inspection Service, and the Postal Inspectors. These terms generally refer to the same law enforcement agency and are used interchangeably. Additionally, some people may also refer to the USPSIS as simply the Postal Police, as they are responsible for enforcing federal laws pertaining to mail and postal services.