Keywords are added to web content so that the sites will be easily found by those who search for specific words. In determining which keywords a site will use they will consider the topic of the content and make a list of all the main words that are linked with that topic. Integrating as many of those words in to web site content is common for ensuring that the content becomes optimized for the various search engines that may be used to access the page.
The purpose of the keyword is to concisely describe the topic of the page. Keywords are monitored for effectiveness and reviews of which keywords have been searched for or linked from will be considered. If the keywords chosen do not result in many page views the site owner will change keywords in order to find the best possible set.