Techniques for search engine optimisation
Keywords
A user searching for a topic on the Internet will use keywords to help locate the relevant sites and pages. If you want your site to be found it should contain those keywords incorporated in an ethical and legal way. It is important to be aware of the correct use of keywords otherwise there is a risk the site will be banned by the search engines and never be found.
Content
The site content should be developed with the keywords in mind. The quality of the content of each page is important. Above all it should be relevant and informative.
A suitable technique is to rank keywords according to their relavance to the page content and then place them in a hierarchical fashion, so that the most important words will be in level 1 headings, then level 2 and so on.
Using keywords as headings and in the body of the text will help search engines to
determine if this is the page to display to the user. The use of the key words within the body of the text is also important. However repetition should be avoided.
HTML tags
HTML tags instruct the browser how to display the page. They also contain other information, which can be used to describe the content such as titles for images or tables. This is particularly useful to non-visual browsers such as would be used by a user with a visual impairment. Proper use of these tags is not only consistent with accessibility guidelines but helps with search engine ranking too.
Title tag
The title tag should be unique for each page, no more than 40 characters in length. Ideally it should incorporate the most important key word for the page.
<title>Search Engine Optimisation</title>
Meta tags
The most important meta tag contains the description attribute. This is the text displayed by the search engine when it returns the results to the user.
Description
<meta name= "description" content =
"Developing a quality web site optimised for search engines">
The description should be no more than 200-250 characters in length.
Keywords
<meta name= "keywords" content = "search engine optimisation">
Most search engine crawlers ignore this tag. However it can be useful as a placeholder for keywords to remind the content writer of important words and phrases to include in the copy. (See later)
Other meta tags
These are irrelevant and ignored by most search engines.
Image tags
The alt attribute provides a textual description of an image.
A meaningful description for an image is not only good practice in terms of accessibility it is
also used by search engines to help locate documents for users searching for images.
<img alt = "search engine optimisation graphic" >
Anchor tags
The text content of an anchor tag should be relevant to the page being linked.
<a href = "seo_faq.htm">Search engine optimisation - FAQ</a>
is preferable to 'Click here'
Title attribute
Any HTML element can have a title attribute. The text is displayed briefly when the cursor rolls over the element. It should be used carefully in the same way as the Alt attribute for the Img tag.
Site map
A site map is a page containing links to all the pages within the site. It is an aid to search engines.
Link popularity
There are three types of link on a website, in-bound only links, out-bound only links and reciprocal links. An in-bound link occurs where another website contains a link to your site. An out-bound link is where your site has a link to another site. Websites that link to each other are said to have reciprocal links.
The single biggest factor for determining search engine popularity is the number of in-bound only links.
Search engine ranking
A search engine spider will index your site and give it a ranking. The algorithms used to calculate the ranking position varies between the search engines. All will use the factors described above to some degree. Ranking is used to help the search engine find the best matches for a users query. A user searching for a particular subject wants quality sites to be returned in the search. The ranking algorithms are designed to find the highest quality results for a set of keywords.
In the early days, unscrupulous web developers could easily spam search engines through excessive use of keywords. Poor, inappropriate sites would often be returned to the user leading to frustration and dissatisfaction with the search engine.
Today, the theory behind in-bound linking is that other sites are more likely to link to yours if you are offering relevant, quality content, hence your site will get a higher ranking. However, recently (Jan 2006) a famous German car manufacturer had its ranking reduced to zero when Google discovered it was using a technique called 'doorway pages'. Here a page having achieved a high ranking due to its relevant textual content, immediately redirects the user to another page.
Reciprocal linking can help your ranking if the site with which you are linked has a higher ranking than yours. Out-bound links have no effect on the ranking position.
Directories
Yahoo and The Open Directory Project (dmoz.org) are the two biggest, free directories. These will provide in-bound only links. There are many smaller directories catering for particular market sectors, some charge a fee while others provide reciprocal links.