If you are borrowing more than 80% of the value of the property, the lender will typically require two things: mortgage insurance (MI) and an impound account for you to pay your real estate taxes and insurance monthly with your mortgage. If you are buying an investment property (for rental), mortgage insurance is usually charged once you borrow over 70% of the property value.
Another option also exists in certain cases. It may be possible to get a second loan to piggy back behind your first loan and thus get rid of MI and impounds. By doing a 75% 1st loan and a 15% second loan, with your 10% down (called a 75/15/10), for example, you are borrowing the same 90% of the purchase price but have neither impounds nor MI. Doing an 80/10/10 is also possible in many situations.