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How Search algorithms work
With the amount of information available on the web, finding what you need would be nearly impossible without some help sorting through it. Google ranking systems are designed to do just that: sort through hundreds of billions of webpages in our Search index to find the most relevant, useful results in a fraction of a second, and present them in a way that helps you find what you’re looking for.
These ranking systems are made up of not one, but a whole series of algorithms. To give you the most useful information, Search algorithms look at many factors, including the words of your query, relevance and usability of pages, expertise of sources, and your location and settings. The weight applied to each factor varies depending on the nature of your query—for example, the freshness of the content plays a bigger role in answering queries about current news topics than it does about dictionary definitions.
To help ensure Search algorithms meet high standards of relevance and quality, we have a rigorous processthat involves both live tests and thousands of trained external Search Quality Raters from around the world. These Quality Raters follow strict guidelines that define our goals for Search algorithms and are publicly available for anyone to see.
Learn more below about the key factors that help determine which results are returned for your query:
Meaning of your query
To return relevant results for your query, we first need to establish what information you’re looking forーthe intent behind your query. Understanding intent is fundamentally about understanding language, and is a critical aspect of Search. We build language models to try to decipher what strings of words we should look up in the index.
This involves steps as seemingly simple as interpreting spelling mistakes, and extends to trying to understand the type of query you’ve entered by applying some of the latest research on natural language understanding. For example, our synonym system helps Search know what you mean by establishing that multiple words mean the same thing. This capability allows Search to match the query “How to change a lightbulb” with pages describing how to replace a lightbulb. This system took over five years to develop and significantly improves results in over 30% of searches across languages.
Beyond synonyms, Search algorithms also try to understand what category of information you are looking for. Is it a very specific search or a broad query? Are there words such as “review” or “pictures” or “opening hours” that indicate a specific information need behind the search? Is the query written in French, suggesting that you want answers in that language? Or are you searching for a nearby business and want local info?
A particularly important dimension of this query categorization is our analysis of whether your query is seeking out fresh content. If you search for trending keywords, our freshness algorithms will interpret that as a signal that up-to-date information might be useful than older pages. This means that when you’re searching for the latest “NFL scores”, “dancing with the stars” results or “exxon earnings”, you’ll see the latest information. Source: https://www.google.com/search/howsearchworks/algorithms/