A margin is the space between the edge of something and where the important part begins. The margins on a page are the blank strips along the sides where you're not supposed to write. Teachers often ask students to use one-inch margins so there's room for comments and corrections.

The word also means the amount by which something succeeds or fails. When a basketball team wins by a large margin, they beat the other team by many points. When a candidate wins an election by a narrow margin, only a few votes separate winner from loser. Scientists need a margin of safety when building bridges: they make them stronger than necessary so even unexpected stress won't cause them to collapse.

In business, profit margin means the difference between what something costs to make and what you sell it for. If you buy lemonade ingredients for two dollars and sell cups for five dollars, your profit margin helps determine whether your lemonade stand succeeds.

Understanding margins helps you know whether you have room to spare or need to be more careful with your resources, time, or effort.