Advertising online is the preferred method because it allows the advertiser to accurately track how many of his advertisements have resulted in an actual sale. When a person clicks on a banner or text advertisement, a cookie is stored in the users' browser. The cookie can track whether the user finally adds the product to cart and then purchases it online. This way, the effectiveness of an advertisement can be easily determined. If many users who visit a certain site end up purchasing the product, more advertisements can be placed on other pages of that site. If a site's referrals do not result in many purchases, then that site is considered non-profitable to the advertiser. This way, advertisers can spend their advertising funds in a more effective way. Compare this to a more traditional advertising medium like the newspaper or television, where there is no way of determining how many of the viewers of the advertisement will actually end up buying it. Initially, the e-advertising did not have the same ability to reach the masses as television or newspapers, but this situation has rapidly changed as more people are taking to the internet.

Note : This document will probably be expanded more in the future as I learn more. If you have any useful information or links to information on advertising, please contact me.