There are two types of incomes linear and residual. How do you know which kind of income you have? Its simple just ask yourself one question how many times do you get paid for every hour you work. If you answered only once then your income is linear. Income sources from a salary are linear. You only get paid once for your effort and if you don't show up for work neither does your paycheck.
With residual income you work hard once, and it unleases a steady flow of income for months or even years. You get paid over and over again for the same effort. Wouldn't be awsome to be compensated again and again for ever hour you worked? Imagine the possibilities of getting paid repeatedly even while you sleep. Imagine the possibilities of spending quality time with your loved ones or even enjoying your favorite hobbies or past times while your income is flowing.