Keyword marketing is increasing your chances of putting your site in front of those people who are searching using your particular Keyword.
This is when companies pay for the use of a keyword. This means when that keyword is searched your site will rank higher on the search engine.
There can be more than one site using the same keyword which then results in a bidding scheme. This is when the two sites fight for the top-ranking space and the search engine takes both the bid and the content of your site into consideration. The search engine then puts which every site they feel is most accurate higher on the ranking.
Keyword marketing is a way to get on the search listing above the organic listing.
An advantage to using Keyword marketing as it increases your chances of reaching the correct customers at the correct time.