PITI stands for Principal, Interest, Taxes and Insurance. Aside from maintenance, these are the core expenses of owning a house. Typically, your monthly payment to your lender or mortgage servicer includes all of these costs.
For example, let's say you buy a home for $250,000 with a 5% down payment on a mortgage loan at 3% interest, 1% PMI, 1% property tax and $1,000/month property insurance. Using our mortgage calculator, you can see that your monthly PITI would be just under $1,500.