A SEO technique used by Web designers to overload keywords onto a Web page so that search engines will read the page as being relevant in a Web search.
Because search engines scan Web pages for the words that are entered into the search criteria by the user, the more times a keyword appears on the Web page the more relevancy the search engine will assign to the page in the search results (this is only one way that search engines determine relevancy, however.)
Search engines often penalize a site if the engine discovers keyword stuffing, as this practice is considered poor netiquette, and some search engines will even ban the offending Web pages from their search results.
Various Methods of Keyword Stuffing
There are several methods of keyword stuffing. One way is to insert repeating keywords within the input type=”hidden” field meta tag or the keyword tag so that the keywords are not seen by the user but are scanned by the search engine.
Another way is to make text in the body of the Web page invisible text, or hidden text, by making the text the same color as the page’s background, rendering the text invisible to the user unless the user highlights the text. This method is called invisible keyword stuffing. Keyword stuffing can also be referred to as keyword loading and spamdexing.
Also see How Web Search Engines Work in the Did You Know . . . ? section of Webopedia.