There are two parts to content marketing PLACEMENT, and about 3 in structure on your website. Here is the general scope:
1. Content marketing is article writing, video publishing, and image creation where you distribute things to other places that will link back to you like Rob said. The purpose they have is to gain attention. Videos and images are great for people on cell phones and also people who don't like to read, and are probably best suited for consumer products but of course that isn't a 100% rule. Articles target readers.
You want readers because readers take action more frequently than non-readers. A statistical example would be that the top-paid CEO's in America read roughly 60 books per year (that's more than 1 per week). And they are the same people who buy everything too, not to mention pay salaries.
2. Content marketing is an SEO factor where you use the keywords in your articles to collect targeted traffic. Research should be done about what keywords you want to target and yet more research again on how many visitors you can expect from them.
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The Way It Works On Your Site
1. Once the user visits your article on your website, you want them to be exposed to several calls of action. This could be an email registration, an account registration, a downloadable product, or a first-sale item. The first sale item built into your article is meant for you to gain an understanding about who is most interested in you.
2. The next phase is to market to your list, which are the people that downloaded something from you or signed up to something from you.
3. Option to buy is important. You need to make the buying process easy for your customers and "remind" them frequently that you sell things. Do it in links inside of your articles and have a "SHOP" section in your navigation perhaps.
So in conclusion, content marketing is a funnel of information-assisted selling.
Also, wait for SEOPub to get here and he will tell you all the stuff I missed in that last post.