SEO is used to ensure a website is well-positioned in the search engine when a potential customer is looking for the product or information that the site provides. For example, a website selling hats will attempt to be at the top of the search engine results pages (SERPs) when a customer types in 'hats' or 'buy hats online' into their search engine.

Optimising a website involves some skill and should be considered at every stage of development. The web designer and builder should be aware of how to create a good website, with usability a key factor. Once the website has been built, the SEO executive or copywriter will work his or her magic and the website will rank highly in the search engines, if everything goes to plan.

To optimise a website, the content must be made suitable for the search engine spider. This spider crawls (hence the name) through the site checking its relevance, content and code. The spider will then assess the site and this will help evaluate the website and process the information to decide where the site will rank in the SERPS for a particular search term.

Search engine optimisation is therefore aimed at making a website appealing to both customers and web spiders. Although the process of making a site usable and making a site appealing to the web spider have been seen as different in the past, developments in search engines have made the two intertwined.

The content of a website is vitally important for the spider and customer to assess the website's suitability. Headings and text should include important keywords that the website is looking to attract. Insert keywords into the content and write attractive sentences that will entice the reader as well as the spider. Good content will not be too reliant on keywords but will ensure that the keywords are regular enough to achieve a good search ranking.

Search engines will attempt to place the most relevant site at the top of their rankings. One of the techniques that is used to assess relevance is the amount of other sites that link to your site. Backlinks must be as relevant as the content, so adding links to irrelevant other sites will not have a positive effect on your rankings.

The SEO novice must attempt to get these basics right before moving on to more progressive techniques such as video-linking, social networking and open identities. New techniques are often labelled as Web 2.0 and Web 3.0 as they refer to changing trends in online marketing as the internet evolves. In an ever-changing environment, the optimiser should ensure the key SEO skills are perfected and develop from there.

These are some of the ways that a website company or individual will attempt to achieve high rankings, but some others are not legitimate and allowed by the strictly-governed search engines. Illegal techniques are referred to as black hat or spamdexing and can result in websites being removed completely from SERPs.

Black hat techniques are developed by innovative webmasters looking to get ahead in the online marketing arena. These ideas are generally successful for a short period before the search engines learn of how the website achieved its rankings. Deceptive techniques have included hidden text, link-farming and keyword stuffing and began as normal SEO practise before being abused by ambitious SEO marketers.

The most successful SEO experts will attempt to bend the rules of SEO without breaking them and finding themselves banned and blacklisted. To succeed in SEO, you must the middle ground between black hat and ambitious, progressive optimisation and use what you learn to achieve high rankings. In a market where change is constant, you must evolve and adapt or risk falling by the wayside.