The Internet is a vast computer database. As such, its contents must be searched according to the rules of computer database searching. Much database searching is based on the principles of Boolean logic. Boolean logic refers to the logical relationship among search terms, and is named for the British-born Irish mathematician George Boole. On Internet search engines, the options for constructing logical relationships among search terms often modify the traditional practice of Boolean searching. The three major Boolean or logical operators used in information retrieval are: (1) AND, (2) OR, and (3) NOT.