Fannie Mae is a company that helps people buy houses. When you want to buy a house, you usually don't have all the money you need. Fannie Mae helps you by giving you some of the money you need to buy your house. Then, you pay Fannie Mae back over time with something called a mortgage. Think of a mortgage like a piggy bank that you put a little bit of money in each month. Eventually, you will have put enough money in the piggy bank to pay Fannie Mae back for the money they gave you to buy your house.