There is a specific tax definition of passive income, known as “passive activity” to the Internal Revenue Service. Passive income is any income you make without actively working or are materially involved. The IRS defines it as any rental activity or any business in which the taxpayer does not “materially participate.” Nonpassive activities, or active activities, are businesses in which the taxpayer works on a regular, continuous, and substantial basis.

The gems and jewellery industry has been economically active in India for several thousand years.[187] Until the 18th century, India was the only major reliable source of diamonds.[183] Now, South Africa and Australia are the major sources of diamonds and precious metals, but along with Antwerp, New York, and Ramat Gan, Indian cities such as Surat and Mumbai are the hubs of world's jewellery polishing, cutting, precision finishing, supply and trade. Unlike other centres, the gems and jewellery industry in India is primarily artisan-driven; the sector is manual, highly fragmented, and almost entirely served by family-owned operations.
The services sector has the largest share of India's GDP, accounting for 57% in 2012, up from 15% in 1950.[165] It is the seventh-largest services sector by nominal GDP, and third largest when purchasing power is taken into account. The services sector provides employment to 27% of the work force. Information technology and business process outsourcing are among the fastest-growing sectors, having a cumulative growth rate of revenue 33.6% between fiscal years 1997–98 and 2002–03, and contributing to 25% of the country's total exports in 2007–08.[194][needs update]
This would only require the investment of your time. Start with a blog on something you love. It could be anything. From a travel blog containing pictures of your travels to a sports blog dedicated to your favorite team/sport. You can blog about anything and everything. It doesn't matter. But write regularly! I've read that an online magazine editor would personally prefer someone who posts something daily over someone who writes long posts once or twice a week.
"Create your own products and services," financial blogger and life coach Michael Tamez tells Bustle. "Any company you could ever work for can replace you at any time. However, your individuality can never be replaced! I encourage you to explore your creative talents and abilities more. What are you good at? How can you monetize that talent and perhaps even build a business out of it? Have you experienced something extraordinary in your life, and because of it, have tons of knowledge and wisdom to share? ... Creating your own products and services can create steady streams of residual income, which pays you continuously, even when you're not working. Essentially, you bust your ass once and get paid for the rest of your life — even when you're sitting on the beach, sipping coconut rum. Just remember this: When you invest in your creative abilities, you become irreplaceable!"
Regardless, it took me around 18 months to start turning a profit online. It started with around $100 per month, then grew to $200 per month. Then it kept growing and growing until, eventually, the money I earned online surpassed what I earned in my regular, 9-5 job. That was last year, and my online income is still growing. Believe it or not, it all came from starting this simple, yet effective, blog.
I would throw in some caution here: if your spouse works at the same company, or in the same industry as you, you are not diversified, and should something happen, you could be in a world of hurt.  Companies do go out of business, companies do lay employees off.  There is nothing wrong with working together, but realize that you are not diversified and you should be trying to maximize other income streams as a result.
Connecting two entities is another great way to make extra money by spending less energy. So can always have an agreement with some business entity to give clients on referral basis and earn a commission. I recently hired a designer for some work and I asked him if he knows someone who can PRINT the designs for me. He referred me to his friend who done the printing work. I am sure he must have got some cut for the referral and there is nothing wrong in it. Its a smart way of earning money.
The appeal of these passive income sources is that you can diversify across many small investments, rather than in a handful of large ones. When you invest directly in real estate, you have to commit a lot of capital to individual projects. When you invest in these crowdfunded investments, you can spread your money across many uncorrelated real estate ventures so individual investments don't cause significant issues.
What I’m doing: My realistic goal is to have a blended annual return of 2x the risk free rate. With a current 5% hurdle, I am not paying down mortgages that cost less than 4%. Debt at 5% is a wash. My realistic blue sky scenario is a 3-4X rate of return over the risk free rate which can be achieved with property, stocks so far for the past five years, and certain private equity investments. Where I am dragging is my blended average CD interest rate of roughly 3% from an old CD coming due. I’ve rolled some money into a 12-month CD with CIT Bank at 2.5%. It’s the best rate I can find. 
Thirst for income is likely to continue with interest rates expected to stay low, keeping government bond yields low for longer and their valuations unattractive.  Looking past bonds, the prices of high-dividend shares are historically high, which limits the likelihood that their dividends will rise markedly from here.  Striving too high for an income target tends to push your portfolio further out on the risk spectrum.