Because keywords are such an important part of the substance of your website content, they require extra special attention. You could even say that keyword usage is a “rite of passage” skill that takes time to acquire. For example, if your site sells church chairs, or knives, you might think that the word “knives” would be the best keyword to utilize. Well, you may or may not be right, but it’s a good bet that this site sells many different kinds of “knives.” Being able to select the right keywords requires a good understanding of your target audience and what they are looking for.
Some unethical SEOs choose to employ renegade tactics such as keyword stuffing. Keyword stuffing is overloading the content or meta tags of the web page with every possible keyword or phrase that relates to the site in many different forms. For example, a bad meta description for our knife site would read as follows: “knife, knives, butterfly knives, switchblade, spring assisted knife, sharp, steel.” Notice that this example has only keywords and no sentence structure. There was no coherency and certainly no call to action inviting the browser to “do” anything.
A good meta description would read something like: “Find a wide variety of knives including switchblade, butterfly and spring-assisted knives at Knife.com. Take a look at our selection of knives and order yours today!” This example is better because it's not stuffed with keywords. Another benefit to this meta description is that it doesn’t just target broad terms like “knife,” but employs other specific search keywords that are related to the site.
Keyword stuffing doesn't work because when the search engine crawler examines your site, its algorithm can quickly determine if keywords are used an unreasonable number of times. If your site contains an unnaturally high density of one single keyword, your site will actually drop in the rankings rather than rise. In severe cases, your site could be removed from the search engine index completely.
Don’t give in to the temptation to stuff your website full of keywords in an attempt to improve your rankings. The result will be the exact opposite of what you are trying to accomplish. You're better off writing good, relevant content that humans and search engines will love.