Any property that you buy to make a profit - either from renting or selling it
Investing in real estate can be extremely profitable venture - it's considered a long-term investment and the way to make money is to have equity, which is the money that you keep after the mortgage is paid off. The 3 main ways to build equity are: (1) your down payment when you purchase (2) paying off the loan's principal, which may take several years since your first years' payments go primarily towards the interest and (3) the increase in the home's value when the property appreciates.
The new capital gains tax also creates an added incentive to invest in a property. For example, if you're single, widowed or divorced, and your home was your primary residence for 2 of the last 5 years before you decide to sell, you can pocket up to $250,000 tax-free. If you're married, you can profit $500,000 without paying any tax.