A major factor of magazine ad effectiveness relative to many other media is the interest of the audience. Magazine readers typically have strong interest in the theme or topic of a given magazine. There are hundreds of magazines often targeting niche interests. If you advertise computer software, for instance, you can finds several magazines related to technology generally and computer software specifically. If you advertise a product or service closely tied to the magazine's theme, you likely reach readers who have natural interest in products or services like yours. Finding this close link between readers and your brand is critical to effectiveness.