When you type one or more words into Google's search field, for example, the search engine first finds all documents in the index that match the search. Often, millions of results appear. It is therefore necessary to sort the documents so that the most relevant ones come first in the search result. Nobody wants to scroll through 12 million pages to find the right link. This is where the algorithm ensures that the most relevant results come up. The search engines' algorithms are, however, kept secret from the public, and exactly how it works is a good question that many are still trying to figure out. There are, however, various guidelines on how to accommodate the algorithms' mechanisms and their way of "thinking". You can read more about what algorithms are and their technical background here.
Google uses a so-called ranking system. It consists of a long series of algorithms. Algorithms take their starting point in your query with various reservations. The factors that change your query into what appears in Google's search field are the relevance of the words, the usability of the pages, your location, settings and source credibility. The date, of course, also plays a major role. These countless different buttons, virtual tools and other unknown factors determine how your search field result looks. Google tries to ensure that algorithms in search have high standards for relevance and search quality. Google therefore uses live tests and thousands of trained quality testers from all over the world to assess the quality. These quality testers are familiar with the various mechanisms that affect the search field. There are strict guidelines that direct users on how they should navigate the internet.
