The notation SO(n) refers to the special orthogonal group in mathematics, which consists of all n x n orthogonal matrices with a determinant of 1. These matrices represent rotations in n-dimensional space, preserving both angles and distances. The "special" aspect indicates that the determinant is constrained to be 1, distinguishing it from the broader orthogonal group O(n). SO(n) plays a crucial role in various fields, including physics, computer graphics, and robotics, where understanding rotations and orientations is essential. For example, in 3D graphics, SO(3) is used to model the rotation of objects in three-dimensional space.