Guide

Search engine optimisation (SEO)

What is a search engine and how do they work?

Search engines allow users to search the internet for content using keywords. Although the market is dominated by a few, there are many search engines that people can use. When a user enters a query into a search engine, a search engine results page (SERP) is returned, ranking the found pages in order of their relevance. How this ranking is done differs across search engines.

Search engines often change their algorithms (the programs that rank the results) to improve user experience. They aim to understand how users search and give them the best answer to their query. This means giving priority to the highest quality and most relevant pages.

How do search engines work?

Search engines use programs, often referred to as spiders, robots or crawlers, to search the internet. These programs are used by search engines to build an index of the internet. However, although most search engines will provide tips on how to improve your page ranking, the exact algorithms used are well guarded and change frequently to avoid misuse. But by following search engine optimisation (SEO) best practice you can ensure that your website is well indexed and remains high in the rankings.

Different search engines

Different search engines use different methods to rank websites. Understanding these methods will help you understand the SEO strategies outlined in this guide.

The three of the most popular search engines are:

  • Google - Google assesses the value of a webpage based on the number of backlinks ie links back to your website. Links from pages that are seen as important by Google weigh more heavily and increase the ranking of the linked pages. Google also analyses the relevancy of the content on the page and other factors like mobile-friendliness. The Google ranking algorithm changes constantly. It can be useful to keep up to date with the latest changes. 
  • Bing - Microsoft's Bing search engine ranks websites based on the webpage content, the number and quality of websites that link to your pages, and the relevance of your website's content to keywords.
  • Yahoo! - Yahoo! began as a manually edited directory. It now uses link analysis tools to determine page relevancy, though content is also important in deciding search relevance. Other factors that are important include backlinks and a good site design.

Google has the vast majority of the search market share. Bing, Yahoo and others make up a much smaller percentage. However, if you are targeting customers in China, keep in mind that Google is blocked by the ‘Great Firewall of China’. Baidu is the biggest search engine in China with over 75 per cent of the search market.

For more detailed information on how to best optimise your website for a particular search engine, refer to their webmaster pages. All the leading search engines provide information and tools to help you improve your SEO.

Types of search engine

There are a number of specialist search engines that allow users to search for specific things like videos, used cars, recipes, flights and hotels. SEO tactics can be used to help your products and services rank well on specialist search engines. YouTube, Facebook and Amazon are examples of popular specialist search engines. 

Rich media search results

Universal or 'blended' search is how search engines present different content types in the search results to users. As well as the traditional text page results, the SERP will also show rich media content, such as images, videos, maps, articles and shopping pages.

Having several different types of content on your website - for example, an instructional video on how to use your product, or a blog - could impact on your chances of appearing on results pages and how highly you are ranked. 

You can use ‘structured data’ on your website to help search engines understand and display specific types of content. This is a code added to the HTML markup. Using structured data mean that information such as review ratings, images, addresses and phone numbers can appear on the search engine results page.