What is keyword stuffing? how does it affect your website SEO?

Keyword stuffing is really Black SEO that makes no sense really. The idea is the place keywords on the page to manipulate rankings for that search term. The issue is search algorithms are smart enough to find out the illegitimate spamming pages.

Build natural content according to a site wide theme and plant the keywords across the content only to create relevance no need to go wild... 

Best term to describe keyword stuffing is 'over optimisation'. in an effort to cheat the search engines, some may opt to insert as many keywords as possible in either the web content or meta descriptions to achieve higher ranking in search results. The good news is; the search engines have improved a lot and are much smarter in picking out negative SEO practices. So while this may possibly work on the short term, it may result to a permanent ban of your site and affect future rankings in search engines.

Hello,

keyword stuffing is essentially adding loads of information that doesn't add value to the content of the site. As its name suggest it may be a very high density of keywords, repeated keywords, or any text created with a spinning program.

Up until recently, this worked as a SEO optimization technique, but from the panda update on, google penalizes this technique.

So if you get a message in your webmaster tools that informs you that it has detected keyword stuffing, the best course of action is to remove the offending parts and request re-evaluation.