No matter which way you do it, it’s passive income—money you earn while you sleep because you put these products up for sale on your website and a customer can buy and download them any time of day or night, automatically. All you have to do is check the sales periodically to see what topics or types of products are selling best so you can make more of those.
You run an accounting firm that specializes in tax preparation, and business was lagging this year. You want to do better next year, so you start a blog on your website and publish posts about some of the common tax-related issues your target customer faces. You write a few posts a week, and eventually those blog posts start to rank in Google and other search engines.