All the pages in the world of Internet are linked each other via links. If one page exists independently, without any links pointing towards it, it will be hidden for search engines. Search engines find a web site through the links placed by these web sites in other sites. When the spider sent by a Search Engine visits a particular page it looks for further links after analyzing the web page. The links placed in a very popular page will be seen by these Search engines as a valuable source of information. Through these links it understands about websites. The keywords mentioned in the WebPages are also an important source of information for search engines. With these keywords and links, they are able to produce relevant results from among millions of web pages.
Search engines regularly update their database with the updated information it fetches from millions of web pages around the globe. It is then stored in a database format for future use. These regular updating periodically makes it more reliable in an ever-changing world.
