Search engine indexing is the process by which search engines discover, crawl, and store web pages in their databases. When a web page is indexed, it means that it has been discovered by a search engine and that the search engine has stored a copy of it in its database.
The process of indexing begins when a search engine's web crawler, also known as a spider, discovers a new web page. The crawler follows links on the page to other pages, and the process continues until the entire website has been discovered and indexed. The information that is collected during the indexing process is used to create a search engine index, which is a database of all the web pages that have been discovered and stored by the search engine.
When a user performs a search on a search engine, the search engine uses the index to identify the web pages that are relevant to the search query. The search engine then ranks the relevant pages according to various ranking factors and displays the results to the user.
Overall, search engine indexing is an important part of the search process, as it allows search engines to discover and store information about web pages, and to make that information available to users who are searching for it.