Abstract: The information present on the World Wide Web is continuously increasing at a tremendous rate. The rate at which the information is growing, requires new techniques to handle and organize this data. Question and Answering System is used to answer the query given by the user in the natural language. Main challenges of Question and Answer system is to give exact answer of question given by the user. This paper gives a thorough overview on the QA system, Types of question, its methods and the related work done on QA systems.

Keywords: Answer extraction, answer ranking, semantic similarity.