Keyword Stuffing is not an optimization method at all. It’s instead a form of spam that happens when search engine spiders, like Googlebot, see keywords used excessively on your page.
Keyword stuffing is a set of activities to manipulate search engine results for a relevant keyword. These activities involve excessive keyword spamming through text or website meta tags. Google search engines downgrade websites from ranking practicing keyword stuffing.
It’s also known as ‘keyword density. The logic behind this technique is that by including “target terms” (the words or phrases people may be searching for) close to each other in their content; these words will show up more often within the SEP index and better match the person who may be looking for information about those words… But it can actually do more harm than good–in fact, Google warns users against keyword stuffing!