Passive income is money you can earn without working a traditional job. This is the opposite of active or earned income, which is generally defined as income received from working at a job or as a contractor.

That’s not to say passive income is easy money — in fact, the opposite can be true. Most ways to generate passive income require a large upfront investment, and the income part comes later. But once you’ve made that initial investment, passive income can pay off for years to come.

To help you compare your options, our editors have compiled a list of nine investing-based passive income ideas. We’ve included the effort level and return potential for each strategy, plus who they might work best for.