Web Mining is a technique to know about user's behavior to access various web pages. Web mining can be defined as the discovery and analysis of useful information from the World Wide Web (WWW) in broad manner. Web mining is basically a technique of Data Mining. Further there are three types of web mining techniques: web content mining, web structure mining and web usage mining. Web usage mining is used to analyses and discovers usage patterns from Web data, in order to understand and better serve the needs of Web-based applications.