As an example, during an easing of monetary policy, the Federal Reserve may instruct the Federal Open Market Committee (FOMC) to purchase Treasury-backed securities on the open market. The purchase of these securities gives money to the people who sold them on the open market. The sellers then deposit any excess funds into a savings account. The extra money in savings accounts gives banks more money to invest.
This is an example of passive income that isn't quite as passive as it may seem. Yes, if you own one or more homes or apartments you can collect regular rent checks from your tenants. But in exchange for that, you need to keep the properties in good working order, along with insuring and paying taxes on them. You may need to chase down rent checks from some tenants, too, and you may have several months without rent checks when you're between tenants.
Great article, I have tried a few over the years. I had a side business cleaning offices for years. It did great, but I hated never being able to take more than 3-4 days vacation, so I eventually gave up. I tried MTurk, but if you multiplied my earnings on an hourly basis, it was a little over $6/hr. My blog is much worse, probably less than $0.25/hr.