距离是对两个物体或位置间相距多远的数值描述，是个不具方向性的纯量，且不为负值。

在物理或日常使用中，距离可以是个物理长度，或某个估算值，指人、动物、交通工具或光线之类的媒介由起点至终点所经过的路径长。

在数学里，距离是个称之为度量的函数，为物理距离这个概念之推广。度量是个函数，依据一组特定的规则作用，且有具体的方法可用来描述一些空间内的元素互相「接近」或「远离」。除了欧氏空间内常见的距离定义外，在图论与统计学等数学领域里，亦存在其他的「距离」概念。在大多数的情形下，「从 A 至 B 的距离」与「从 B 至 A 的距离」的意义是相同的。

Distance is a numerical description of how far apart objects are. In physics or everyday usage, distance may refer to a physical length, or an estimation based on other criteria (e.g. "two counties over"). In mathematics, a distance function or metric is a generalization of the concept of physical distance. A metric is a function that behaves according to a specific set of rules, and is a concrete way of describing what it means for elements of some space to be "close to" or "far away from" each other. In most cases, "distance from A to B" is interchangeable with "distance between B and A".