Target marketing is the process of focusing on a select and specific group of people.
Determining your specific target audience is most important to the success of your business. For example, if you are marketing baby products, it would be wise to place ads in an ezine whose subscribers are new parents. But it wouldn't be wise, to place ads in an ezine whose subscribers are interested in software products. To be effective, you need to advertise to people who are interested in or have a need for your product. There are tons of ezines out there.