Minor: For a square matrix [aij] or order n, the minor Mij of aij, in A is the determinant of the square sub-matrix of order (n-1), obtained by leaving (or striking off) ith row and jth column of A.
Cofactor: Cofactor of an element aij in a square matrix [aij] is termed Cij.
Cij = (-1)i+jM)ij
Mij is the minor of element aij in a square matrix [aij].
Minors and cofactors are defined for elements of a square matrix only. They are not defined for determinants.