A decimeter is a unit of length in the metric system, equal to one-tenth of a meter. It is commonly used in various fields, such as science and education, to measure shorter distances. For example, a standard ruler often has measurements in centimeters and decimeters, making it easier to visualize smaller lengths. In practical terms, a decimeter is equivalent to 10 centimeters or 100 millimeters. This unit is useful for measuring objects that are larger than a centimeter but smaller than a meter, such as the height of a small plant or the width of a book.