Keyword frequency is a measure of the number of times keywords occur within a page's text. It's kind of related to the concept of keyword density. The thinking is that search engines want to see a word used more than once to make sure it’s something you’re really talking about. The best number of times to repeat a key word is 3-7 times.
Don't get overly clever and try to use tiny or invisible text to put keywords at the beginning of your pages. Search engines look for this, and when they find it they call it spam and they’ll probably reject your site for it.
So, in a nutshell, you want to:
- Include at least 100 words in page text
- Use keywords at the beginning of the page
- Place keywords close to each other
- Repeat keywords 3-7 times for every 100 words
