How search engines operates?
 

Search Engines have two major functions- crawling and building an index, and providing answers by calculating relevancy& serving results.

1. Crawling and Indexing: Crawling and indexing the billions of documents, pages, files, news, videos and media on the World Wide Web.
2. Providing Answers: Providing answers to the user queries, most frequently through list of relevant pages, through retrieval and rankings.

Thanku so much for sharing such a basic concept of link building and i hope you will update more on this concept.