How Do Search Engines Work?

It’s useful to think of search engines as performing four functions – crawling, creating an index, calculating rankings and relevancy, and serving results to users browsing the net. If you have a website it’s very useful to know how search engines operate because you depend on them to bring people to your site. Through knowing how they work you can better understand the techniques used by search engine optimisation experts and keep website optimisation in your mind when you think about any aspect of your site. In this short article we’ll look at the ways search engines operate and think about ways you can benefit from being in the know.

Indexing and Crawling
Think of the World Wide Web as resembling an underground rail network in a big city like London. Each station stop along the line is a unique document (most often a web page but sometimes a JPG, PDF or other file). Search engines are required to ‘crawl’ the entire network to find all the stops along the way, and so they use the best paths available to them – links. Crawling and indexing then involves billions of documents on pages, news, files, media and videos on the World Wide Web. With the information gleaned from crawling, search engines are able to provide answers to queries from users, most often in the form of lists of relevant sites on results pages. They use ranking to decide which sites will be most relevant to users.

Through links, automated robots called ‘spiders’ or ‘crawlers’ are able to reach the many billions of connected documents on the web. When the search engines have found a page, the next job is to read them and to store selected sections of pages on massive hard drives to be recalled for the benefit of users in answer to queries. This is a monumental task when you consider how many billions of documents need to be stored, each for accessing within a fraction of a second. Search engines have constructed huge data centres to hold all this information and they’re located in cities all over the world.
Datacentres are truly massive, containing thousands of machines and processing truly vast quantities of information. It’s no wonder they need to be so big when you consider the speed at which users of the Internet expect search results to appear.

Search Engines Are There to Provide Answers
When a user enters text into a search box, they are asking the search engine to perform some very sophisticated tasks. The search engine is required to trawl their ocean of information to find pages relevant to the search performed and display them to the user and also to grade the pages in terms of relevance. Relevance here means importance or value to the user, and deciding it is not as simple as it may sound, as many factors need to be taken into consideration.

It is because of this process that search engine optimization specialists exist, because every business or enterprise on the Internet wants to be ranked highly by search engines in order to feature when someone performs a search.To search engines, relevance means more than a site having the words you searched for displayed prominently. In the past it used to be almost as simple as this, but not any more. Today hundreds of factors influence results and the process is very sophisticated.

What Do Search Engines Look for?
This is a big question but put very simply, search engines these days see popularity as relating to importance. So the more popular a page is already, the more likely it is to appear on a results page after you’ve typed in key words to look for.
The task is not performed manually, of course, and complex algorithms comprising of hundreds of components are used to ‘rank’ pages.

How Can We Turn This Knowledge into Results for Our Website?
Though the algorithms are complex, any free search engine optimisation analysis by an SEO Company will reveal many ways in which a business can improve its chances of ranking highly with search engines. The main factors are the number and quality of inbound links and content, key words etc.

As a rule, search engines rank sites highly when they’re easy to use and offer good quality content. Tricks that used to improve rankings are no longer of much use, as search engines employ ever more sophisticated means to offer users a better experience of searching online.