Keyword density is an important factor for search engines when they rank web pages. It helps determine if your content goes well with a keyword and can help attract more attention to the page from potential searchers looking in that niche area of interest, leading it up on the SERPs (Search Engine Results Pages).
Keywords are used by many people who use online search engines such as Google or Bing to find what’s most relevant for them. Keyword Density tells you how often a specific word appears on-page – this information aids in determining which words best match content topics while increasing visibility within various results pages much like PPC ads do but without spending any money!