SEO Practices That Can Cause Penalties or Bans
Revised on September 17, 2008
There are a number of search engine optimization (SEO) practices that can lead to a website being penalized or banned from search results, these are sometimes referred to as black hat practices. Search engines have become better able to detect these practices and so sites that have used these practices for long periods of time may suddenly get penalized or banned.
Hidden Text
Hidden text is any text that is hidden from a user visiting a web page, but is visible to a search engines crawler. This is accomplished by either making the text the same color as the background or by hiding the text using CSS.
Cloaking
Cloaking involves returning a different web page when search engine's crawler requests it than what a user would receive. The page may be slightly altered or could be completely different and is designed exclusively for the search engine.
Keyword Stuffing
Keyword stuffing is the overuse of certain words in attempt to affect search results; this can be in web pages contents or in the ALT text for images.
Link Schemes
While linking to other websites is acceptable, excessive amounts of links in the form of link exchanges (linking to each others website) to boost a website's ranking is not.
Doorway Pages
Doorway pages are web pages that immediately redirect a user to another web page. Similar to cloaking, the doorway page is designed exclusively for search engines.
More information is available in the Google, Yahoo, and MSN/Live Search webmaster guidelines.