When you write a blog post on your website, that article immediately goes out to your followers. But the content also remains on the website for others to find via search engines or social media. Each time somebody reads your content, there’s the potential to serve them an ad, product for purchase, or affiliate link (many links in this post are affiliate links). Each set of eyeballs that read your content carry the potential for passive income.

In equity valuation, residual income represents an economic earnings stream and valuation method for estimating the intrinsic value of a company's common stock. The residual income valuation model values a company as the sum of book value and the present value of expected future residual income. Residual income attempts to measure economic profit, which is the profit remaining after the deduction of opportunity costs for all sources of capital.