How do Search Engines Work? By Natasha O'Flynn

What is a Search Engine?

A search engine is a program that searches for items in a database that correspond to keywords typed in by the user. They are used especially for finding particular sites on the World Wide Web. Different search engines include Google, Bing, Yahoo, DuckDuckGo and


What is an algorithm?

An algorithm is a list of rules you need to follow in order to solve a problem. For example, making a cake - here, the algorithm is the cake recipe.

How do search engines use Algorithms?

Search engines use very complex algorithms to determine what results it should display. They also use them to rank the search results.

How do search engines rank their results?

Every search engine has developed a formula for ranking web sites. Every search engine uses a different formula, which is why the results will be different between Google, Yahoo, Bing, and other search engines. These formulas, known as algorithms, are constantly changing as the search engines try to achieve better results. The process of improving how your websites rank on the web is known as search engine optimization or SEO for short. The results obtained are always changing as different things get more popular or go out of fashion

How do you get higher up in the rankings?

There are many things you can do to achieve higher in the rankings, for example:

  1. Update your content regularly - this is important as it makes the information more relevant to the reader.
  2. Have a link-worthy site - focus on having clear, relevant links which use keywords rather than 'click here'.
  3. Use alt tags - they allow search engines to locate your page which is crucial.
Focus on making all the information relevant and always use alt tags.

Indexes and Spiders

Google indexes list all of the webpage that google knows about. To do this, google uses something called spiders. Spiders are software programs. They start by getting a few webpages by asking various questions - does that webpage contain the words you've typed into the search engine? How often? Is it from a quality website? Does it contain the keywords in the title? Altogether, it can ask over 200 questions. After it has a few websites, the spiders follow the links on the pages and the links on those pages and so on, until they have indexed a large chunk of the web, a lot of which is relevant to what the searcher initially searched.

Software spiders

How can you trust online content?

  • Check grammar - things like wrong spelling are often a very quick giveaway that the website isn't a quality one.
  • Look for proof - quotes, links and references.
  • Look at the design of the webpage - a good design can be a sign of a quality website.
  • website is likely to be unofficial if the address (URL):
  • Check the URL - if it doesn't include : 'gov', 'ac', '', 'org', or '.com' at the end of the address, or is very long, it is likely that the website isn't very trustworthy.

What are google ads?

When you search something into google and press enter, it displays your results in under a second. However, it also shows ads along the top and right hand side of the page, and sometimes further down the results as well. The results that are not adverts are known as the 'organic results'.

The parts outlined in red are the ads, the others are the organic results.


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