A proper fraction is a fraction where the top number (the numerator) is smaller than the bottom number (the denominator). In other words, it represents less than one whole thing. The fractions 1/2, 3/4, and 5/8 are all proper fractions because in each case, the numerator is smaller than the denominator.

Think of cutting a pizza into eight slices. If you take five slices, you have 5/8 of the pizza: that's a proper fraction because you have less than one complete pizza. If you somehow took nine slices (maybe you grabbed a slice from another pizza), you'd have 9/8, which is called an improper fraction because the numerator is bigger than the denominator. That means you have more than one whole pizza.

Proper fractions always have values greater than zero and less than one. They describe parts of a whole: half a cookie, three-quarters of an hour, or two-thirds of your homework. When you see a proper fraction, you know immediately that you're talking about an incomplete amount, something less than a full unit. Understanding proper fractions helps you compare amounts, add and subtract parts, and make sense of any situation where you're working with pieces rather than complete wholes.