In geometry, a three-dimensional (3D) space is a mathematical space in which three values are required to determine the position of a point. Alternatively, it can be referred to as 3-space or, rarely, tri-dimensional space. Most commonly, it means the three-dimensional Euclidean space, that is, the Euclidean space of dimension three, which models physical space. More general three-dimensional spaces are called 3-manifolds. The term may refer colloquially to a subset of space, a three-dimensional region, a solid figure.