According to [URLnf="http://contentmarketinginstitute.com/what-is-content-marketing/"]CMI[/URLnf], "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."
In other words, it focuses on using words to sell. As opposed to traditional marketing, where you would buy X amount of ads, a content marketing strategy would focus on writing and building a reader's base that would ultimately convert into customers.