Contextual advertising according to www.webopedia.com is advertising on a Web site that is targeted to the specific individual who is visiting the Web site. A contextual ad system scans the text of a Web site for keywords and returns ads to the Web page based on what the user is viewing, either through ads placed on the page or pop-up ads. For example, if the user is viewing a site about sports, and the site uses contextual advertising, then user might see ads for sports-related companies, such as memorabilia dealers or ticket sellers.
Contextual advertising is considered to be more effective than banner ads, but usually less effective than search engine marketing like Google Adwords. Not surprisingly, the cost of a contextual ad is usually less than that of traditional search engine marketing.
Trying to capture the attention of your target market without this potential client having actively initiated a search is not a simple task. Once your prospect has clicked on your contextual ad, make sure the landing page you drive them to information described in the ad. Remember that content is what first sparked the interest of the prospect into reading the ad.