Fraction is a part of something. When objects are measured, often the measurements do not come out in whole units. A book may weigh between 2 and 3 pounds. The amount over 2 pounds is a fraction of a pound. A board may measure between 10 and 11 inches long. It is 10 inches plus a fraction of an inch long. The word fraction comes from a Latin word meaning to break. Fractions result from breaking a unit up into a number of equal parts. A unit can be broken into any number of parts. If you break a stick into two pieces, however, you do not necessarily have two halves of the stick. In order to have two halves of the stick, you must break it into two pieces of equal length.

Fractions are written in numerical form as two numerals separated by a line: 2/5.

In arithmetic, a fraction generally stands for the number of equal parts into which something has been divided and the number of those parts that are being considered. For example, the fraction 2/5 represents two parts of something that has been divided into five equal parts.

The fraction form is also used for (1) expressing division, (2) representing a ratio, and (3) stating a rate. In expressing division, the fraction 2/5 may indicate two divided by five for example, dividing two candy bars equally among five people. A ratio is a comparison of two quantities that are both measured in the same units. A ratio may compare a part to a whole or a part to another part. For example, if there are two girls and three boys on a debating team, the ratio of girls (a part) to team members (the whole) is two to five (2/5). The ratio of girls (a part) to boys (another part) on the team is two to three (2/3). In mathematics, any number that can be written as the ratio of two whole numbers is called a rational number (see Ratio). Rate is the relation between two quantities that are measured in different units. For example, a basketball team may score at the rate of two goals per every five minutes of play.

The different uses and meanings of fractions are closely related. Often, understanding one of the meanings of fractions will help make understanding other uses easier.