Search indexing content online: Functionality and optimization

Google and other search engines index online content so it can be displayed to Internet users in search engine results. Search engine optimization is essential as it enables other machines and Internet users to find online content.

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What is a search engine index?

Search indexing predates the Internet and describes the practice of compiling data. Archives and libraries regularly use search indexing, whereby keywords which reflect the topic of a document are assigned. Users or visitors can then easily source material by entering a keyword into the database, for example, an author’s name, a year, or a specific title, which will result in the index showing the items which correspond to the keyword. It works similarly on the Internet.

Search indexing on the Internet

Search engines such as Google operate on a similar principle to an archive’s or library’s index. When a user enters a keyword into a search engine, the index will be searched and show the results it finds in a specific order.

Indexing is made possible through online tools. Search engines use crawlers or search bots to scan the Internet, visit new websites, analyze their content, assign keywords, and add it to the search engine’s index. This means that text documents and their updates, as well as images, videos, and other file formats are all being captured by crawlers.

Since there is so much content for the same keywords nowadays, the search results are presented to users in a specific order. Websites are ranked and the content which is most likely to be relevant to the user appears first on their list of results. Google Ranking Factors determine which content is most relevant for a search result. Many of these factors are known, but the weighting is not always clear and is also frequently changed by the search engines. However, giving the user the best possible experience is always the goal.


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Search indexing and search engine optimization

Websites must be indexed by search for users to be able to access their content. However, just indexing is not always enough given the huge volume of web content available these days. Search engine optimization is crucial to ensure that a website is properly indexed and ranks as highly as possible in the relevant searches. But what exactly is meant by optimization?

Triggering website indexing

In the early days of search engines, it sometimes took several days or weeks for a crawler to discover and index a new page. To speed up this process, it was possible to register a website directly with Google. Thankfully, this is no longer necessary as the search bots are now constantly crawling and indexing new content quickly.

Guiding crawlers during indexing

Nevertheless, website operators can and should support crawlers in fully indexing the relevant content. For example, it is a good idea to register for the Google Search Console (formerly: Google Webmaster Tools) and create a sitemap with the relevant pages and subpages. The robots.txt file indicates to the crawlers which information, pages, file types, and directories should be excluded from the search and indexing. Individual pages can also be excluded through the noindex tag.

There are other commands which can be placed in the header of a website, which provide the crawler with important information, such as which version is the original in case of duplicates (canonical tag).

Optimizing indexing and how to improve in the rankings

Web content should always be fully optimized so the website can place in the top rankings on Google. Optimizing texts for keywords and meta data, i.e. the title and the description, which are the displayed search result, should be completed in accordance with known specifications. Internal and external links, structuring of content, assignment of file names etc. belong to the long list of steps which are important in search engine optimization.


Keep an eye on the development and search indexing of your website with tools like Google Search Console or IONOS rankingCoach — the algorithm for indexing is constantly changing and improving.

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