Keyword: A keyword is a word entered into a search engine (such as Google, Bing, or Yahoo) in order to find content on the web related to that word. Keyword searches can also be performed on individual websites and databases.

Google is the most popular search engine in the world, accounting for approximately 65-70% of all search volume, so much of current keyword research is focused on gaining the best results on Google. Google users, as with those of other search engines, enter a keyword or keyphrase into the site's search field, so they can find related websites, blogs, videos, news, maps, and other content. For example, if a user wants to find information on artisan cheeses, they might input the word "cheese" or the keyphrase "artisan cheese" into the search bar. Users looking for specific types of cheese might also search related words, like "Gouda" or "Brie" or search for cheeses from specific regions of the world.

In search engine optimization (SEO), keywords are used strategically on a client's website or in other web content created for that client in order to direct search users to the client's site. So an artisan cheesemaker in Portland who want to gain customers online might have his site optimized to display higher in search results for phrases like "Portland cheese" and "artisan cheese in Portland." He may also want to have marketing content built around cheese-related terms, so his SEO agency would use a keyword research tool, like Google's AdWords, to find relevant words and phrases.

One thing to avoid in SEO and content creation, however, is keyword stuffing. This practice places as many keywords and keyphrases as possible into web content. As a result, the copy is virtually unreadable, and search engines like Google will flag such content as spam.