Natural Search Optimisation

What factors determine search positions?

All search engines use different factors to determine which websites are most appropriate for keyword searches, but almost all agree that the most important factors are:

Site Content

Website content is generally considered to be the most important factor in determining a websites relevance to keywords. When a search engine evaluates a website it looks for a number of factors to determine what keywords are relevant. Page titles, URLs, headers, content, links and formatted text all have different weightings associated with them so getting the balance right is important.
As search engines have become more intelligent content has become increasingly important. In the early days many search engines just looked at meta-tags (tags that describe a web page) which specified which keywords a website was relevant for. Unfortunately these are now often ignored due to companies trying to cheat the system and with a push by search engines to find more relevant ways of judging content. 
As a basic rule keywords should appear in the content between 4-8% and will have a higher rating factor if they are contained within heading tags, page titles and URLs or emphasised with the use of bold and italic tags.
The “freshness” of content has also become a major factor in recent years with search engines now looking for websites to keep content up to date and show that the website is still being used and maintained.

Link Popularity

Google, more than most search engines, uses the popularity of a website to gauge its relevance and importance. By using a system that represents a link from page “a” to page “b” as a vote for page “b” Google  created a system that rewards websites for obtaining inbound links. This technique has now been widely adopted by most search engines.
As with anything however, this system has evolved to become more sophisticated. Now taking into account the importance of the website that is providing the link, where the link is found on the website, how many other links are on the website, and what terms are used in the link, running an inbound link program is now a major factor in search engine optimisation.

Site Architecture

Building a website in “well formed” code not only makes it more readable for people with disabilities but helps search engines “bots” read the content of your website rather than the nonsensical code that tells a browser how to display it.
A website needs to make the process of reading content as easy as possible to search engines otherwise it risks having content missed entirely.
One such problem is often seen with older content management systems where pages are produced with parameters such as www.website.com/page.asp?id=2. Although most search engines can now differentiate between pages with parameters using techniques such as URL rewriting to give pages individual names greatly improves readability and search engine ranking.
www.website.com/page.asp?id=2 can become www.website.com/valuable-keyword-link.aspx