Information retrieval is a science of gathering information from unstructured data, the online information source i.e., www. WWW contains data of heterogeneous types and of high dimension. Retrieving information from such database is a tedious work. Many researches are going on, to find a best optimal solution. A search engine is the tool for retrieving information from www. The internet helps the user to get the required information from www. A search engine respond to the user-need by answering their query, contains: Database, Web crawler, and Ranking algorithm. The optimality of the search engine is based on the ranking algorithm.