====== On-Page Factors ======
On-Page factors are related directly to the content and structure of the website. This normally consists of pages written in the HyperText Markup Language but also applies to other document formats that are indexed by search engines, for example Microsoft Word or PDF formats. On-page optimization involves modifying keyword frequency in the URL, Title, Headings, Hypertext Links and Body text. It may also involve reducing redundant HTML codes (aka cruft) produced by Web page authoring tools and restructuring the site to produce better linked and focussed page content.
Many search engines now discount the weight given to on-page factors because they give too much scope for abuse by SEO experts. In theory the visible parts of a web-page are less prone to manipulation as they have to make sense to readers. However doorway pages with redirections and clever use of style sheets enable different content to be served to search engines and end users.
Each page should target between two and four [[keywords]] directly related to the contents. If you feel the need for more keywords then consider splitting your content into separate pages. The Uniform Resource Locator (URL) should contain keywords, separated by hyphens without being too long, around 128 characters is probably a sensible upper limit for the entire URL. The Title tag should contain the keywords with no stop words but arranged to make sense.
On Page Optimization
This should be the first tag in the Head section of the page. There is evidence that search engines give more weight to factors higher up the page. The content should be properly structured with the use of Heading (H1, H2, H3 etc) tags containing relevant keywords. Search-engines will only index a limited amount of text in HTML tags and using too many keywords will dilute the focus. Don't spam any of these tags, this won't be effective and could result in a penalty.
Many website designers spend a lot of time creating Keyword and Description meta tags. Although these may be read by search engines, for example the description tag is used by Yahoo! to provide a short description of the site in the Search Engine Results Pages, they are not used for ranking pages.
Personally I don't bother with them as they bulk out pages for little real benefit. Both Google, Yahoo! and MSN Search will use the text they find on the page as a description so make sure your first header and sentence describe the contents. However some search engine watchers say that the new Microsoft search engine, currently in beta tests, puts some weight on meta-tags. There is also evidence to suggest that search engines give more prominence earlier in the page and some engines will only index a limited amount of body text so making the first paragraph punchy is a good idea.
Image alternate-text tags (ALT tags) are only indexed where the image is part of a hyperlink. However ALT tags are useful for non-graphical browsing and should be employed correctly.
Comments are not indexed. Use bold/strong/italic attributes where appropriate.
Write natural copy aimed at the end user and not search engines. Don't worry too much about [[keyword density]] for the contents but take the opportunity to include keywords combined in different phrases and orders and create [[anchor text]] to related internal pages. Keep the number of links to fewer than 50, and probably less and don't repeat identical outbound-links. Theme related pages should be at the same level in the site hierarchy and be linked through the site's menu structure and site map. At least one page at the same level should link back to the home page so that search engines that have traversed a deep-link can index the rest of the website.
For any other document format, e.g. PowerPoint, Adobe PDF etc make sure you at least have a descriptive document title. Try to avoid formats that search engines find hard to understand, even where a search engine can index a format it will carry less information than plain old HTML. Avoid using images to replace text, except occasionally in hyperlinks. Avoid formats such as flash, shockwave and sitemaps where there is no alternative text. Avoid HTML Frames which some search engines find hard to navigate, use Style Sheets (CSS) instead. Style Sheets should also be used to reduce the amount of formatting within documents. Keep pages to less than 100 kilobytes and preferably not much more than a screen full of text. Where Javascript or Flash menus are used include plain-text links at the bottom of the page. These will ensure all search engines index the rest of your website.
Other factors directly under the control of the website is the amount of content. Large websites generally rank better than small websites for a number of reason. Search engines also like fresh content and will spider this more frequently. A regularly updated news page, even a blog, can provide deep links to the rest of the website.