In this project we use inverted index to build an information retrieval search engine. The point of using an index is to increase the speed and efficiency of searches of the document collection. Without some sort of index, a user’s query must sequentially scan the document collection, finding those documents containing the search terms. Consider the “Find” operation in Windows; a user search is initiated and a search starts through each file on the hard disk. When a directory is encountered, the search continues through each directory. With only a few thousand files on a typical laptop, a typical “find” operation takes a minute or longer.