Content marketing is, at its core, a fairly simple idea. You create content, then put it out there for people to see, and consume. That content draws and audience, and that audience sticks around for more content. In time the audience associates you with the content they like, and thus is positively inclined toward you. That means down the line, your audience would be more likely to support you, and their loyalty to your content can translate into loyalty to your business.
That’s all pretty abstract, though, so let’s use a more concrete example. Let’s say you ran an independent bookstore, and you decided to start a YouTube channel doing bad book readings. You find the worst books that come into the store, and make a performance out of dramatically reading them for your audience. It gains a following, and pretty soon you do in-person events as well as the channel. Users who watch the channel go to your website, or walk through your doors, because they want to shop at the store that makes those videos.