Direct response marketing is the discipline of advertising that asks the audience to take an immediate, measurable action — call a number, click a link, fill a form, send a check, buy now — and judges its own performance on the resulting response rate rather than on brand awareness or recall.
The category traces through 20th-century direct-mail copywriters — John Caples, Eugene Schwartz, Gary Halbert, Dan Kennedy — whose principles (specific offers, clear calls to action, headline-as-promise, the Johnson box, tested-against-control) defined the craft long before digital channels existed. The internet inherited the discipline almost wholesale: PPC ads, landing pages, email funnels, and conversion-rate optimization are all direct-response in genre, and the underlying assumption — that every ad is testable and every audience response is data — became the default of contemporary performance marketing.
Direct response sits opposite brand advertising in the classic taxonomy, though in practice most modern marketers blend the two: brand work softens the response, response work monetizes the brand.