Keyword density refers to the percentage of times a keyword or phrase appears on a Web page compared to the total number of words on the page. For example, if a keyword occurs 12 times on a Web page with 400 words, the keyword density is 3 percent. While search engines don't necessarily use keyword density as a ranking factor, you can use it to make sure that you're incorporating keywords into your Web page content. Keywords in your content is an indication that your Web page is relevant to people's Web searches.
The best practice is to incorporate your keywords and variations on those keywords (i.e., "dome tent," "dome," "tent,") as many times as you would naturally in your content. If you're writing quality content that people want to read, this should happen without much effort.
How Visitors See It
How Search Engines Use It