Be aware that this is very expensive and can run into the thousands of dollars per month for even a single search phrase. One piece of software we use is WebPositions , which allows us to see where we list for a variety of keywords in the major search engines. Though this can help to alleviate curiosity, it is also a good tool if you really want to make search engine ranking a project. The purpose is to drive people to your site by bringing them from other places on the 'net. The most popular is banner advertising, which is displayed on a page and allows a visitor to click on that ad and go directly to the advertised site.
Sites charge per thousand times someone can view the ad.
Some sites will charge you only if a visitor clicks on the ad, not just sees the ad. This is one of the best methods of driving traffic to your site, although it can be costly. Web sites offer space to display banners, and many attract 1 out of every 100 of their visitors to go to your site. This may not seem like a lot, but banner ads also offer branding - creating awareness of a site. Besides the often high costs, you are paying for the potential that someone will visit your site through the ad, with the risk that no one will.