Content marketing is a strategic marketing approach focused on creating and distributing valuable, relevant, and consistent content to attract and retain a clearly defined audience — and, ultimately, to drive profitable customer action.

The key word here is “valuable.” It’s what changes this definition from one that could describe almost any form of advertising or marketing. You can tell if a piece of content is the sort that could be part of a content marketing campaign if people seek it out, if people want to consume it, rather than avoiding it