Keywords are one of the most important ways that Google connects online visitors with content. The concept is simple enough; having users’ common search terms in your content helps to ensure that they find your website.
Keywords should be included at a natural frequency in your site’s content. They shouldn’t be “stuffed” as to appear forced, but they should be regular enough that it’s clear what you want to be found for. Consider “long tail” keywords as a supplement to the obvious ones: A combination of many lower traffic keywords can often bring you more traffic than a few high traffic keywords.