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Understanding search engines

SEO is the practice of increasing traffic to your site through non-paid search engine results pages. This article explains more.

Search engine optimisation (SEO) is the practice of increasing traffic to your site through non-paid search engine results pages (SERPs). This is also known as organic SEO.

In the Digital Marketing Fundamentals microcredential version of this course, you’ll have an opportunity to explore SEO alongside search engine marketing (SEM) to learn how to gain traffic and visibility from both organic and paid searches.

For now, it’s helpful to understand that an organic search is conducted through search engines and via clicks on a non-paid result (for example, clicking on a result in the search engine results pages). Organic searches are combined with SEO to increase website traffic as part of inbound marketing.

Organic SEO is an online marketing strategy that ensures your website ranks highly and is visible whenever someone uses a search engine to find solutions relating to your product or service. Successful strategies use both on-page and off-page actions to get more traffic to the website.

  • On-page SEO establishes the SEO strategy for your website or blog by tailoring it to specific keywords.
  • Off-page SEO is action outside your website that affects your rankings within SERPs. It follows those actions by validating your reputation and ensuring people are aware of the content you are creating.

Basic search engine functions

Here are the essential functions that a search engine uses to find and generate search results efficiently.


Crawling is a necessary action for any search engine. ‘Spiders’ scour the internet to find the codes, website addresses, and content for each URL and find the best match for your search query.

The spiders search for new content, but they are also designed to periodically crawl through all known pages to see whether any changes have occurred to the page’s content since it was last ‘crawled’. When changes are detected, the search engine updates its index to the new information. Spiders use several algorithms. They can search a wide range of websites at the same time and simultaneously collect large amounts of information. They begin by looking at a few web pages and then follow links on those web pages to find new URLs.


Indexing uses all the content found in crawling and then organises and stores that information. The index catalogues and organises:

  • detailed data about the content and topical relevance of each web page
  • a map of all the pages that each page links to
  • the clickable (anchor) text of any links.

As a feature, it is designed to exclude unnecessary words and articles (‘the’, ‘a’, and ‘an’). When the common text is eliminated, the index lines up content to be displayed in the search engine results page (SERP) for relevant searches so that it can be found easily.

The index is the database with which search engines like Google store and retrieve data when a user types a query into the search engine. Before they decide which web pages to show from the index and in what order, search engines apply algorithms to help rank those web pages


Ranking displays and delivers content that answers the user’s search query in order from the most relevant to the least relevant results. Whenever someone performs a search, the search engine scours their internal index for relevant content that matches the user’s query. This content is then ordered by relevance – this is known as ranking.

It’s safe to assume that high-ranking websites are more relevant to the search engine query. Rank considers factors such as the best user experience, location, language, device type, and quality.

Graphic shows how search engines find results. It starts with the user. The keyword typed if passed to search request. Then it leads to the database index. Search request is passed to a database server that contains indexes of various keywords. For the database index, it then leads to the results. Search results are returned about the keyword. There are spiders aka crawlers which compile lists into indexes for faster searches. Spiders crawl the web in search of information about websites. Click to enlarge this image

Sub-strategies of SEO

The primary SEO strategy can have many sub-strategies:

  • Keyword research is a strategy to find and analyse search terms when people use search engines such as Google. This data plays a significant role in the SEO strategy because it gives you information about which topics are most popular and the things people care about.
  • Link building happens when a link directs other websites to link to your website. Every time such a link leads traffic to your website, your search ranking improves.
  • On-page optimisation helps your website’s elements to rank higher and land on the first page of search results. For example, your URL structure ensures no links break so that anyone visiting your website can click on all elements. You can also streamline your site’s navigation to ensure your website’s speeds are optimal.

Search engine results page

Search engine results pages generate (SERPs) each time a user searches with specific terms or keywords (for example, ‘tax support apps for freelancers’). Every query and its corresponding results are unique, even if you have used the same search engine and the exact keywords or phrases before. This is because each search engine uses factors beyond the search terms to customise the experience.

These factors are:

  • physical location
  • browsing history
  • social settings.

When you use the same parameters to repeat your search, you might feel that your SERPs are identical. That’s not the case. They might look similar and have most of the same results, but each has its subtle differences determined by the three factors listed above.

Screenshot of Google search results. Arrows are pointing to "paid results" and "Organic SEO results." Click to enlarge this image

Search engine result pages can give you a paid result or an organic result. Paid results generate revenue for the search engine operator because advertisers often bid for keywords. Organic results, on the other hand, are all of the other non-paid search results. Organic SEO determines where you show on the SERPs. Being high on the SERPs means you are doing an excellent job optimising your page for SEO. We’ll cover the paid results in more detail soon.

Why is organic SEO important?

Search engine optimisation is essential because you want people to find you online. Other strategies, like using social media, can generate traffic to your website, but a lot of the traffic is still directed through the search engine and a frequent user will find organic search results more credible.

For example, if you are a clothing store specialising in blue t-shirts, and someone searches ‘blue t-shirt’, you’ll want to drive that person to your website to buy your products. A well-executed organic SEO strategy will help drive quality traffic to your website for free.

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