What is DM- Direct Marketing

According to wiki

Direct marketing is a sub-discipline and type of marketing. There are two main definitional characteristics which distinguish it from other types of marketing or advertising. The first is that it attempts to send its messages directly to consumers, without the use of intervening media. This involves unsolicited commercial communication with consumers or businesses. The second characteristic is that it is focused on driving purchases that can be attributed to a specific "call-to-action." This aspect of direct marketing involves an emphasis on trackable, measurable results (known as "response" in the industry) regardless of medium.
Direct marketers also use media such as door hangers, package inserts, magazines, newspapers, radio, television, email, internet banner ads, pay-per-click ads, billboards, transit ads, etc. And according to Ad Age, "In 2005, U.S. agencies generated more revenue from marketing services than from traditional advertising and media."
If the ad in the medium asks the prospect to take a specific action--call a free phone number, visit a website, return a response card, place an order, visit a PURL, complete a survey, etc.--then the effort is considered to be direct marketing. Direct response or direct-response advertising are both synonymous terms for direct marketing.