Indexing is a critical component of what a search engine does. Without indexing, all of the pages Googlebot crawls have nowhere to live — and the ranking systems don’t have the data they need to function. If Google is unable to index your site, it will not appear in search results.
The fundamentals of a search engine
Let’s start with the fundamentals of what a search engine does. A search engine is an incredible piece of technology, but its operation is divided into three major components: crawling, indexing, and ranking. Crawling is the process of spidering the web and finding content, indexing is the process of reading pages and storing them in a database, and ranking is the process of determining which page to rank for a specific user query.
A search engine must discover content in order to add it to the large index. Crawling refers to the process of using robots to trail the web in search of new and updated content. These crawlers look for content that may be useful to users by using links and sitemaps. After locating that content, the indexing process begins. You can determine how well your site works with or against these robots by improving its crawlability.
Indexing entails comprehending the content and filing it in the appropriate location. After discovering the content, Google must read and comprehend it before categorizing it. To do so, it must first parse the page, or translate it into a computer language that it understands. After that, it renders the page — just like a regular browser — to discover the content and how it appears. After that, it uses the signals and information on that page to file it in the appropriate location within Google’s index — a.k.a. the big filing cabinet.
Finally, a search engine must be able to rank the results based on a user query and present them to the user in an appropriate manner in the SERPs. The ranking process entails understanding the user’s question and retrieving the most relevant content to answer those questions. The ranking algorithms have a significant impact on this process, and they have a plethora of variables to consider.
After locating the most relevant results, a search engine presents them to the user in a logical manner. This could be a regular SERP spot, something rich like a knowledge panel, or something local if the topic is local.