Abstract-Web mining is an exciting discipline in the domain of data mining as well as in classification/clustering. Identifying the usage patterns of users is very important in utilizing the vast information available in the World Wide Web. Web usage mining entails identifying usage pattern and has many practical applications. It focuses on techniques that have the potential to predict user behaviour while the user interacts with the Web. The aim of this paper is to provide a general view on web usage mining and its importance for designers and those interested in e-commerce and website personalization. The paper explains in detail the process of web usage mining and the different techniques used for pattern discovery. Also, it illustrates the different applications and tools used for web usage mining. Finally, it explains some current issues and challenges such as privacy and scalability, which are important issues in web usage mining.. Index Terms-Privacy, usage mining, web mining, web personalization.