An identity matrix is a special type of square matrix that plays a crucial role in linear algebra. It is defined as a matrix in which all the elements of the principal diagonal are ones, and all other elements are zeros. For example, a 2x2 identity matrix looks like this: {1, 0, 0, 1}. When any matrix is multiplied by an identity matrix of compatible dimensions, the original matrix remains unchanged. The identity matrix is often denoted by the symbol {I}. It serves as the multiplicative identity in matrix multiplication, similar to how the number 1 functions in regular arithmetic. Identity matrices can be of any size, such as 3x3 or 4x4, and are fundamental in various applications, including solving systems of equations and performing transformations in computer graphics.