What are ethical methods of SEO?

From Wikipedia:

So-called "Ethical" methods of SEO involve following the search engines' guidelines (Google, Yahoo) as to what is and what isn't acceptable. Their advice generally is to create content for the user, not the search engines; to make that content easily accessible to their spiders; and to not try to game their system. Often webmasters make critical mistakes when designing or setting up their web sites, and "poison" them so that they will not rank well. Ethical SEO attempts to discover and correct mistakes, such as menus not-readible, broken links, temporary redirects, or a generally poor navigation structure that places pages too many clicks from the home page.

Because search engines are text-centric, many of the same methods that are useful for web accessibility are also advantageous for SEO. Methods are available for optimizing graphical content, even Flash animation (by placing a paragraph or division within, and at the end of the enclosing OBJECT tag), so that search engines can interpret the information.

Some methods considered ethical by the search engines:

• Using a robots.txt file to grant permissions to spiders to access, or avoid, specific files and directories in the site
• Using a short and relevant page title to name each page
• Using a reasonably sized description meta tag without excessive use of keywords, exclamation marks or off topic comments
• Keeping the page accessible via links from other pages on the site and, preferably, from a sitemap
• Developing links via natural methods: Google doesn't elaborate on this somewhat vague guideline, but buying a link from an off-topic page purely because it has a high PageRank is probably not considered acceptable. Dropping an email to a fellow webmaster telling him about a great article you've just posted, and requesting a link, is most likely acceptable.

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