Passive income is attractive because it frees up your time so you can focus on the things you actually enjoy. If a doctor wants to earn the same amount of money and enjoy the same lifestyle year after year, they must continue to work the same number of hours at the same pay rate—or more, to keep up with inflation. Although such a career can provide a very comfortable lifestyle, it requires far too much sacrifice unless you truly enjoy the daily grind of your chosen profession. Additionally, once you decide to retire, or find yourself unable to work any longer, your income will cease to exist unless you have some form of passive income.
Residual income is the amount of net income generated in excess of the minimum rate of return. Residual income concepts have been used in a number of contexts, including as a measurement of internal corporate performance whereby a company's management team evaluates the return generated relative to the company's minimum required return. Alternatively, in personal finance, residual income is the level of income that an individual has after the deduction of all personal debts and expenses have been paid.