Indexing is an important part of what a search engine does. Without indexing, all the pages Googlebot crawls don’t have a place to live — and the ranking systems don’t have the input they need to do their work. If Google can’t index your site it can’t appear in the search results.
The basics of a search engine
Let’s start by looking at the absolute basics of what a search engine does. A search engine is an incredible piece of technology, but the workings of it come down to three main parts: crawling, indexing, and ranking. Crawling has to do with spidering the web and finding content, indexing with reading the pages and putting it in a database, and ranking with determining which page to rank for a specific user query.
Crawling
A search engine needs to discover content to add it to the big index. The process of doing that is called crawling as it is literally using robots to trail the web in search of new and updated content. These crawlers use links and sitemaps to find content that might be useful for users. After finding that content, the process of indexing begins. By improving your crawlability you can determine how well your site works with or against these robots.
Indexing
Indexing is about understanding the content and filing it in the proper place. After finding the content, Google has to read and understand it before they can put it in the right buckets. For this, it first must parse the page or, in other words, translate it in a computer language that it can understand. After that’s done, it renders the page — like a regular browser does — to discover the content and what it looks like. When that’s done, it uses the signals and information on that page to file it in the proper location inside Google’s index — a.k.a. the big filing cabinet.
Ranking
Lastly, a search engine has to have a way to rank the results based on a user query and present it in a proper way to the user in the SERPs. The ranking process consists of understanding the question the user is asking and retrieving the most relevant content fit to answer those questions. The ranking algorithms heavily influence this process and they have loads of variables to go on.
After finding the most relevant results, a search engine serves these to the user in a way that makes sense. This might be a regular spot in a SERP or something rich like a knowledge panel, or something local if the topic is locally oriented.
What is indexing at Google?
Indexing is the process of organizing data in a structured way with the goal of helping find the information quickly when asked for. Search engines crawl millions of pages, extract the data and put that data in a big bin called the index. Without a proper, highly-optimized index, search engines would have no way for their algorithms to quickly extract the relevant content.
The process of indexing has a couple of steps. After discovering a piece of content during the crawling process, a parser is going to look at it and determine what it is. The parser recognizes structural elements like titles, links, headings, and more. It also identifies the text and tries to connect words to topics and entities. During parsing, it might encounter errors that make it hard for the parser to fully understand the page.
If the page does translate well, the system will use a browser and try to render it to see a more accurate picture of the content, the design, and the user experience. All these factors determine how a search engine sees and values your site. All of this influences your performance in search.
After reading the page, the contents — text, images, videos et cetera — will be analyzed and classified in the index. The data will be sorted and weighted to determine relevancy. For that, Google uses an inverted index to map all the words to the place in the index, making them easier to discover during the ranking process.
How to influence indexing in Google?
Roll out the red carpet for Google, so to say, if you want them to properly index your site. You need to do everything you can to make your site easy to crawl. Take away technical barriers and improve the discoverability of your URLs.
Keep your robots.txt clean and don’t block pages that you don’t need to block. Update your XML sitemap, check the pages you’ve — accidentally? — noindexed with robots meta tags. Improve your internal linking structure. Have a ton of underperforming pages? It might be a good idea to do something about these low-quality pages. Also, regularly check Search Console to see if Google found errors on your site. There are more things you can do to optimize your crawl budget.
In other words, make sure that the technical SEO of your site is on point. Luckily, Yoast SEO can help you with a lot of the technical bits.
Keep in mind that it might take a while for Google to index your site. It might also not index everything you have. In the case of indexing, having better content helps. If Google finds the millionth bad article about a popular topic, it won’t get a high priority from them.
A short primer on indexing in search engines
A search engine needs to do three things before it presents your content to visitors: crawling, indexing, and ranking. In this article, we’ve given you a basic overview of the different processes, with a focus on indexing. By improving your technical quality and your content quality, you increase the chance of Google properly indexing your pages.
What is indexing in regards to Google? – Yoast.