key performance indicators (KPIs) : The yardstick by which an organization measures the success of its Web site. KPIs are based on a company’s overall business goals, and the role their Web site plays in achieving those goals. KPIs are specific to a company, and are not influenced by industry averages or competitors' KPIs.

keyword : A word relating to Web site content that search engines use to determine whether the site is relevant.

keyword density : The measurement of the number of times a keyword or keyword phrase appears on a Web page, compared to the total number of words on the page.

keyword phrase : A search query containing two or more words that Web page content relates to.

keyword stuffing : Putting every word, not just relevant ones, into the content of a keyword tag; repeating keywords over and over again.