A web site server is able to identify distinct users by using a unique identifier associated with each client computer system requesting access to a web site. The unique identifier comprises an Internet address, such as an Internet Protocol (IP) address, and a time value associated with each client computer system requesting access to the web site. On starting up a web browser, an application program or browser plug-in may synchronize the internal clock included with the client computer system with a global time standard. A web site server may determine the uniqueness of the client computer system by comparing unique identifier records of users accessing the web site. A user may be identified as distinct if no matching record exists in the database. Users privacy is also protected as the unique identifiers are erased when the client computer system's user exits the web browser or powers down the computer.