Google Search Engine:
Initaially Google company launched their site as a search engine. Slowly it became very famous an most of the people started to use this site for searching content on internet. Google searches and displays almost all kind of results avaliable on internet in just a few seconds. This had made google one of the most top rated search engine in the world.
Looking at the popularity of google, the google team decided to extent their site further. So they started providing E-mail service. This service also became popular. Nowadays Google provides many many services like E-mail, search engine, Community sites, Blogging, Clander etc.
Google provides best service in all fields which keeps it at the top.