Passive income differs from active income which is defined as any earned income including all the taxable income and wages the earner get from working. Linear active income refers to one constantly needed to stay active to maintain the stream of income, and once an individual chooses to stop working the income will also stop, examples of active income include wages, self-employment income, martial participation in s corp, partnership.[4] portfolio income is derived from investments and includes capital gains, interest, dividends, and royalties.[5]
It’s been almost 10 years since I started Financial Samurai and I’m actually earning a good income stream online now. Financial Samurai has given me a purpose in early retirement. And, I’m having a ton of fun running this site as well! Here’s a real snapshot of a personal finance blogger who makes $150,000+ a year from his site and another $180,000 from various consulting opportunities due to his site.

Investing in rental properties: Another form of real estate investment, rental investments (i.e. becoming a landlord) could steer you down the passive income path of steady monthly rent checks that you can use to pay off a mortgage loan on the rental property. After the mortgage is paid off, those monthly checks go right into your bank account -- potentially for years to come. 

If you have a blog or other type of site, you can build affiliate links to different services on the website. Many people use Amazon as an affiliate partner. For example, if you are a beauty blogger writing about different products, you can set up Amazon affiliate links on your blog so that whenever someone buys the product you mention on Amazon, you receive a percentage of the sale. Amazon is not the only affiliate partner out there. Here is good, in-depth information on affiliate marketing. 
Leonardo da Vinci is another example of someone who was a "wide achiever," in the words of Roman Krznaric, author of "How to Find Fulfilling Work." Da Vinci was alternately a portraitist, an inventor, and a scientist. Krznaric says that in light of decreasing job security today, spreading yourself among several different jobs, as da Vinci did, is probably a smart thing to do.
Most of us think of investment income as just the cash flow we get from bank interest, bonds, share dividends and property rents, some of which comes via a super pension.  But a more complete view is to also consider how growing the value of your investments can add to your spending potential.  This total return approach generates income from both income and growth to optimise spending from your portfolio across all market cycles, aligning cheap and expensive investments to your goals.