What is function and parts involved in search engine?

Internet search engines having three parts in which the functions can be performed and they are as follows:

A spider is also known as crawler or bot, this travels from one page to another page and visits the complete page.

It represents the page that needs to be searched on the web site and displayed on the search engines.

It includes the reading of the website using the hyperlinks on all the pages and there is communication that takes place from one page to another.

Catalog or indexing is being done that is created by the programs that compile the pages being read from the web sites.

Program that receives the search request and it has its own comparison with the indexing that needs to be done to have the results located.