In measure theory, the **Lebesgue measure**, named after French mathematician Henri Lebesgue, is the standard way of assigning a measure to subsets of *n*-dimensional Euclidean space. For *n* = 1, 2, or 3, it coincides with the standard measure of length, area, or volume. In general, it is also called *n*-dimensional volume, *n*-volume, or simply **volume**. It is used throughout real analysis, in particular to define Lebesgue integration. Sets that can be assigned a Lebesgue measure are called **Lebesgue measurable**; the measure of the Lebesgue measurable set *A* is denoted by λ(*A*).