The notation GL(n) refers to the general linear group of degree n, which consists of all n x n invertible matrices with entries from a given field, typically the field of real or complex numbers. An invertible matrix is one that has a non-zero determinant, meaning it can be multiplied by its inverse to yield the identity matrix. GL(n) plays a crucial role in various areas of mathematics, including linear algebra, geometry, and group theory. It captures the idea of linear transformations that preserve vector space structure, making it essential for understanding symmetries and transformations in higher-dimensional spaces.