Residual income is when you continue to get paid after the work is done. This includes royalties from books, movies, or songs and also income that comes from real estate or business investments where you don’t actually have to be present to earn it. For example, Bill Gates is still making a residual income from Microsoft even though he isn’t working there anymore.

Jon, you always keep it real and I LOVE that about you and your writing! You are so right! There’s always an amount of work that goes into creating “passive income” or becoming a blogger who monetizing with services and courses. Thanks for being honest about how long it can take to truly master the required skills. Frankly, I’ve done my 4+ years of undergrad and grad school and what I’ve been learning in the last 2-3 years as I’ve dug deeper into improving my copywriting and blogging skills by taking classes with yourself and other trustworthy mentors is giving me the best foundation to help me build my freelancing business and ultimately step away from my 9-5. For me, it’s all about who I work for, under what conditions, when, and for how much, rather than a “no-work-at-all” lifestyle. That’s totally unrealistic. And I appreciate you, as a well respected “Guru” yourself, for saying so!
As a person that reads blogs I love it when people add affiliate links of the products they’re talking about because I don’t have to search for them. For example, when I’m deciding which crafts I’ll make with my kids it saves me a lot of time to click on the affiliate links of the products so you’re helping out your reader as well as making side income. See here how I link to products in crafts.
​I’ve been into home décor lately and I had to turn to Etsy to find exactly what I wanted. I ended up purchasing digital files of the artwork I wanted printed out! The seller had made a bunch of wall art, digitized, and listed it on Etsy for instant download. There are other popular digital files on Etsy as well such as monthly planners. If you’re into graphic design this could be an amazing passive income idea for you.
However, you should pick a niche and blog about that. If you're launching a money related blog, maybe it'll be about how to make money in real estate or simply how to make money online. Pick the niche and stick to it. If it's a diet and fitness related blog, maybe the niche is the Ketogenic diet, the Atkins diet or some other form of diet or fitness.
Another benefit of investing in rental properties is the loan pay down. If you obtain a loan to buy the property, each month your tenants are paying off part of the loan. Once the mortgage on the property has been paid off, your cash flow will increase dramatically, allowing your mediocre investment to skyrocket into a full-fledged retirement program.
This book is a definite must read, and in the top 5 out of this list.  My favorite use for this book is to help people decide what business model to pursue – for a start anyway.  ie info product v membership site v affiliate marketing.  Since Joel compares them all and shows you the major challenges for each (along with how-to guides), the task becomes a lot easier.