Index

An index is the directory of a search engine: crawlers like the Googlebot capture pages, store them, and only then make them discoverable. Only indexed URLs can rank in search results.

For the term index, there are different designations: With a few exceptions, however, an index refers to an overview or list of data that can be assigned to a specific topic, for example. In this sense, an index serves to look up information. Such directories also exist on the internet for pages or help to structure the World Wide Web. They are important for every web search.

Among the best-known indexes are those directories created by search engines like Google. They are important for every SEO expert. With the help of so-called web crawlers, these machines scan the internet and read the content of each domain and URL. This process is called crawling. They use the links below and within various websites to search a page. Specifically, this means that a crawler jumps from link to link, thus moving from one domain to another. Every webpage, subdomain, and URL that a crawler essentially scans is added to the search engine's index, meaning it is indexed. The collected data is sorted according to various criteria and incorporated into the data set. Through the index, Google or another search engine can include a page in the ranking and deliver the respective results for a search query. The Google index is the most important web index.

How do search engines work with the website index?

Without an index, a web search engine would not function, as it would not have a database to deliver results for search queries. This means the search engine must primarily ensure that the data of a website is found and adopted. This is done via web crawlers that continuously search the Internet during the crawl process. At Google, this crawler is known as the Googlebot, or bot for short. To be able to process search queries, search engines bring the collected data of the index into a meaningful order (created according to their criteria), which webmasters and SEO specialists better know as ranking factors. These ranking factors are not secret, but their weighting is, as this is referred to as the algorithm. One of the greatest challenges of a good categorization of the index is the semantics of a search query, as a term can always be ambiguous. Therefore, every content on a website must have a consistent semantic environment. Especially high-quality content thrives on this, to display the appropriate results in the SERPs for each search.

In addition to the procurement and categorization of the index, a search engine also ensures that it is a current directory of web-based information in this case. For this reason, pages are repeatedly visited by web crawlers so that the most current version of a page is indexed and found in the results of a search engine. Therefore, a one-time optimization of a website is not sufficient. If updates like Panda or Penguin are launched, a ranking can deteriorate if content no longer meets the new criteria. Therefore, a website should always be adapted to the new standards to be listed accordingly in the Google index or other directories.

Criteria for the web index: which page is included in the ranking?

As already mentioned, search engines like Google categorize web content with crawlers according to certain criteria. These include the ranking factors for pages used in search engine optimization. Examples of this are a page's content and appropriately incorporated keywords, as well as technical SEO factors such as loading times. The link structure of a website is also important. How many backlinks lead to a page? Are the links of high quality? Do the link providers match the content of one's own website?

On the other hand, there are also criteria that have nothing to do with the ranking of a page or cannot be optimized. This refers to websites that, for example, display content that violates the law. These are not included in search engines' indexes. However, this does not mean that these pages are not accessible; they are just not found by the average user. And this user still most frequently uses a search engine on their "journey" through the web.

In general, a website can be removed from the Google index through a penalty. A penalty is a punishment if a page grossly violates the Google Webmaster Guidelines, commits copyright violations, or resorts to Black Hat SEO.