There are three common ways for servers to implement session tracking: 
               
                  
                  -  A unique ID may be placed into the URL of subsequent pages. 
- A unique ID may be placed in the query parameter of subsequent pages. 
- The server sends a cookie that contains a unique identifier with the response. The user agent saves the cookie, and then includes the cookie with the
                     next request. 
                  
BIS uses the third method, cookies, to identify sessions.