Search engine optimisation therefore focuses on the mainstream search engines and directories that index millions of individual web pages and which generate the greatest volume of traffic.

The most important search engines and directories include:

AllTheWeb
AltaVista
AltaVista (United Kingdom)
AOL (United Kingdom)
AOL Web Sites
AskJeeves
AskJeeves Teoma (United Kingdom)
Excite
Google
Google (United Kingdom)
HotBot
Lycos (United Kingdom)
MetaCrawler
MSN
MSN (United Kingdom)
Webcrawler
Yahoo Directory
Yahoo Directory (United Kingdom)
Yahoo Web Results Yahoo Web Results (United Kingdom)

Why Search Engines are Important

Search engines are the internet's most popular type of web site and internet users will quite often adopt a search engine as their home page.

When users search the web using key words the search engines will produce a list of ordered results. This list can feature a number of web sites ranging from just a handful to many thousands. The results of search engine searches are listed in order of relevancy and usually contain 10 web sites on each page.

• 93% of consumers worldwide use search engines to find and access websites.
  Source: Forrester Research
• 57% of internet users search the web every day and 46% of those searches are for product information or services.
  Source: SRI
• Attracting a loyal audience to your website is best achieved through top search engine listings.
  Source: Forrester Research Media Field Study
• 85% of qualified Internet traffic is driven through search engines, however 75% of search engine users never scroll past the first page of results.
  Source: Seventh WWW User Survey - Georgia Institute of Technology
• Users looking for products on-line are far more likely to type the product name into a search engine (28%) rather than go into an engine's "shopping" channel (5%) or click on banner ads (4%)
  Source: March 2001 Jupiter Media Metrix and NPD

How Search Engines Work

In response to a search request, search engines provide a list of results, placed in order of relevancy to the search term used. Each page of results usually contains 10 web pages. The ranking your web site achieves within these results is dependent on the specific algorithms used by the search engine to determine its relevancy to the search term. Search engines use software agents, known as 'robots' or 'spiders' to gather text from your site for 'indexing' in their database. The action of these agents visiting your site and following links between pages is known as 'spidering'.

Search engines generally only 'index' text content, including page titles, meta keywords, meta descriptions and alternative image text. This can then be analysed for the frequency, relevance and prominence of specific words and phrases in relation to user searches and compared to that of other sites. Search engines also use 'link popularity' within their algorithms to help assess the relevancy of your content. 'Link popularity' refers to the number of relevant links your site receives from other sites.

How Quickly Search Engines Index

Search engines receive thousands of registration requests every day and have to work hard to maintain the integrity and relevance of their data. As a result, the delay between submitting a registration and the site or page actually being indexed can range from a few days to many months.