The notation "A⁻¹" represents the inverse of a matrix A. In linear algebra, the inverse of a matrix is a matrix that, when multiplied by the original matrix, yields the identity matrix. The identity matrix acts like the number 1 in regular multiplication, meaning that A * A⁻¹ = I, where I is the identity matrix. Not all matrices have inverses; a matrix must be square (having the same number of rows and columns) and have a non-zero determinant to possess an inverse. If a matrix does not meet these criteria, it is referred to as "singular" and does not have an inverse.