Search Engine Optimisation - keyword metatag
This article addresses the question of whether 'keyword stuffing' is a worthwhile practice, or not. For a broader view of SEO, please see our whitepaper: search engine optimisation.
Background: web developers insert keywords into the KEYWORDS attribute of the META tag in each page on a website, "most often to help search engines categorize them correctly" . However, as modern search engines have numerous ways to categorise pages, "Meta elements have significantly less effect on search engine results pages today than they did in the 1990s" .
None-the-less, the tag is still used, and one of the questions that arises from that is, is repetition of keywords a bad idea, or not? The answer is as follows:
- "...a Web site repeating the same meta keyword several times may have its ranking decreased..." 
- "'Keyword stuffing' refers to the practice of loading a webpage with keywords ..." and may cause Google to block your site. 
- "Don't fill your page with lists of keywords..." - this may cause Google to block your site. 
- "Repeating keywords in the Meta tags ... has been ineffective since 2005." 
- "Never insert the same word twice in a row" 
- "repeat a particular word too often in a meta keywords tag and you could actually harm your page's chances of ranking well." 
- "do not repeat words" 
- "Be very stingy with how many times you repeat a word, and donít repeat a keyword more than twice." 
- "avoid multiple entries which could be mistaken as 'spam'" 
- "Don't repeat keywords more than twice" 
In September 2009, Google restated their position on the keyword metatag: "Our web search disregards keyword meta tags completely". 
Other notable points from the Wikipedia article:
- "Major search engine robots are more likely to quantify such extant factors as the volume of incoming links from related websites, quantity and quality of content, technical precision of source code, spelling, functional v. broken hyperlinks, volume and consistency of searches and/or viewer traffic, time within website, page views, revisits, click-throughs, technical user-features, uniqueness, redundancy, relevance, advertising revenue yield, freshness, geography, language and other intrinsic characteristics." 
- "No consensus exists whether or not the keywords attribute has any effect on ranking at any of the major search engines today. It is speculated that it does, if the keywords used in the meta can also be found in the page copy itself. With respect to Google, thirty-seven leaders in search engine optimization concluded in April 2007 that the relevance of having your keywords in the meta-attribute keywords is little to none. However, the same article also suggests that Yahoo still makes use of the keywords meta tag in some of its rankings. Yahoo itself claims support for the keywords meta tag in conjunction with other factors for improving search rankings." 
- "Google does not use HTML keyword or meta tag elements for indexing. The Director of Research at Google, Monika Henziger, was quoted (in 2002) as saying, "Currently we don't trust metadata because we are afraid of being manipulated." ... Other search engines developed techniques to penalize Web sites considered to be "cheating the system". For example, a Web site repeating the same meta keyword several times may have its ranking decreased by a search engine trying to eliminate this practice, though that is unlikely. It is more likely that a search engine will ignore the meta keyword element completely, and most do regardless of how many words used in the element."