The term “indexing” describes a method of information collection that has the goal of compiling an index of documents or other data. This information is sorted according to certain criteria, for example by assigning keywords to a document based on its content.
The prepared documents together with their assigned keywords form the index, which enables faster searching and filtering of information.
Modern database management systems (DBMS) work with an index which ensures that a list of relevant content is displayed when certain keywords are entered. Search engines such as Google work in the same way. When a user starts a search query, it searches the index instead of the entire internet to find relevant search results.
How does content indexing work on the internet?
The indexing of web content is a complex and time-consuming process. It uses different methods from various scientific fields such as computer science and information science. Leading search engines such as Google, Yahoo, and Bing rely on crawlers to index web content. These are autonomous software programs that work in a similar way as robots, which is why they are often called search engine bots or robots. Crawlers navigate through the internet and continuously add web content to the search engines' index. The content is sorted and divided into hierarchical levels using an algorithm. This hierarchy is the main factor that determines the order in which search results are displayed when users enter a search query.
Google and other search engine providers are constantly working on improving their indexing algorithms. Google, for example, updates important features of its index at irregular intervals. By introducing the Caffeine Index, Google made a fundamental change to how content is being indexed. This update ensures that new content can be indexed and presented to users in a much faster way. Especially web content that is updated regularly - such as podcasts or videos - can be found more quickly.
How can you influence indexing?
The basic requirement for including a website in a search engine's index is that crawlers are able to find it. In the case of a new website, you can simply suggest it to the search engine provider. For Google, this is possible via the URL Inspection Tool in the Search Console.
Another important requirement for indexation is that your website can be accessed and analyzed by search engine crawlers. One way to ensure this is to include meta tags in the source code of your website. Meta tags are usually placed in the head section of an HTML file and are primarily used to describe a website's content so that crawlers can better understand it.
The current index coverage of your website can be checked in Google’s Search Console, for example. To use this service, you need to register your website first. You can also upload a sitemap of your website in Google Search Console to ensure that all of your subpages are found and indexed by Google. A sitemap contains a list of a website's relevant sub-pages and helps crawlers analyze it in a faster and more efficient way.
Importance for SEO
Understanding how web content is indexed by Google is of great importance for SEO, since each website has to be indexed before it can appear in search results. Just a few years ago, site operators often had to wait for a long time until their website was crawled and indexed by Google. Thanks to new technologies and solutions, this is now happening almost in real-time. You can influence this process to a certain extent and ensure that your site is crawled, indexed, and displayed in a prominent position in the search results. This is possible through various on-page and off-page SEO measures as well as by providing high-quality content. It is important to always be up to date, as Google and other search engine providers regularly make changes to their algorithms to increase their indexing efficiency and eliminate existing vulnerabilities in their system.
Organic index vs. paid index
Search engines like Google typically use two types of index: an organic index and a paid index.
The organic index is used to generate relevant organic results for users’ search queries.. The ranking of your website in organic search results is calculated by a search engine specific algorithm. High rankings mean that your website is positioned in the upper range of search results. As part of search engine optimization, there are various options available to influence a website’s ranking in organic search results. However, you always have to follow the guidelines of the search engine operators.
Besides the organic index, search engines often also have a paid index. It allows you to have your website displayed as a paid ad in a prominent position above the organic search results. Google, Bing, and other search engine providers offer special programs for this purpose. Google calls this ad service “Google Ads” and Bing calls it “Microsoft Advertising”. For paid search results, rankings are primarily based on advertisers’ bids for relevant keywords.