The order of a matrix refers to the number of rows and columns that a matrix has. It is represented as "m x n," where "m" is the number of rows and "n" is the number of columns in the matrix. For example, a matrix with 2 rows and 4 columns has an order of 2 x 4. The order of a matrix is important because it determines whether certain operations on matrices are possible. The number of elements in a matrix is equal to the product of its number of rows and columns.