Indexing in SEO refers to the process by which search engines organize information and websites that they know about. It is a necessary step before a website can be displayed in search results. Indexing involves storing and categorizing information and content found on websites, ready to be displayed in search engine results pages (SERPs) . The process of indexing includes three primary functions: crawling, indexing, and ranking. Crawling involves scouring the internet for content, looking over the code and content for each URL found. Indexing involves storing and organizing the content found during the crawling process. Once a page is in the index, it is in the running to be displayed as a result to relevant queries. Ranking involves providing the pieces of content that will best answer a searchers query.
Indexing is an essential part of SEO because content that is not in the index has no possibility of ranking for a search result. It is the final step of a pipeline that every web page needs to go through to be retrieved and displayed to search engine users when their queries are relevant to the given page’s content. To optimize a website for indexing, it is important to make a crawler's job as easy as possible and not put any obstacles in the way that prevent the site from being indexed.
