Search engine

Search engines crawl web pages, store content in an index and deliver matching results for search queries, sorted by relevance and quality. Google dominates with around 90% market share in German-speaking countries; AI search systems are increasingly changing search.

What is a search engine and how does it work?

A search engine is, put simply, a program that can be used to search large data stores – above all the World Wide Web – for information. The results appear as a list of links, increasingly supplemented by direct answers, images, maps and AI-generated summaries.

Since the early days of the web, search engines have been the most important tool for finding information when you know what you're looking for but not where it is. Operation is similar for all of them: you enter a search query into a box and receive a list of matching results.

How a search engine works

Search engines work in three steps. First, crawlers (bots) search the web by following links and retrieving pages. The content is then analysed and stored in an index – a huge database recording words, topics, entities, links and much other information about each page. Finally, for a search query, the search engine doesn't search the web but its index, evaluates the matching pages and displays them in ranked order.

For website owners, this is the reason to do search engine optimisation (SEO): only pages that are crawled, indexed and rated well appear high up in the search results (SERPs) and get clicked.

Each search engine has its own algorithms that determine which pages rank for which search queries. Many factors are known – such as relevance, content quality, links and technology – but their exact weighting remains secret.

Market leader: Google

There are numerous search engines worldwide, but Google dominates by a wide margin: in Germany, Austria and Switzerland, around 90% of search queries go to Google, even more for mobile searches. Other well-known search engines in German-speaking countries are:

Bing, Ecosia, DuckDuckGo, Yahoo, Startpage and Qwant

Microsoft's Bing is Google's most important competitor. Its index is also the basis for several other services: Yahoo, Ecosia and DuckDuckGo rely wholly or partly on Bing results, as does ChatGPT's web search. Ecosia uses its revenue to finance tree-planting projects, while DuckDuckGo and Startpage promote privacy protection.

There are also search engines for special target groups or areas, such as blinde-kuh.de as the first German-language search engine for children, and vertical searches within platforms such as Amazon or YouTube, which are the first port of call for many product and video searches.

Yandex, Baidu and new AI search systems

Google isn't the market leader in every country. In China, Baidu dominates because Google isn't available there; in Russia, Yandex has a large market share. This is relevant for internationally active shops wanting to enter these markets. At the same time, AI search systems such as ChatGPT, Perplexity or Google's own AI Overviews and AI Mode are fundamentally changing search: users ask questions in dialogue and receive directly formulated answers with source references. For websites, it's becoming more important to appear as a source in these answers too.

With its search engine, Google has not only fundamentally shaped user behaviour on the internet but also laid the foundation for modern search engine marketing with Google Ads.