Web usage mining[8] also known as web log mining is the application of data mining techniques on large web log repositories to discover useful knowledge about user’s behavioral patterns and website usage statistics that can be used for various website design tasks. The main source of data for web usage mining consists of textual logs collected by numerous web servers all around the world. There are four stages in web usage mining: (1) Data Collection : users log data is collected from various sources like server side, client side, proxy servers and so on, (2) Preprocessing : Performs a series of processing of web log file covering data cleaning, user identification, session identification, path completion and transaction identification, (3) Pattern discovery : Application of various data mining techniques to processed data like statistical analysis, association, clustering, pattern matching and so on ,(4) Pattern analysis : once patterns were discovered from web logs, uninteresting rules are filtered out. Analysis is done using knowledge query mechanism such as SQL or data cubes to perform OLAP operations.