There are six different kinds of matrices: square, symmetric, triangular, diagonal, identity, and orthogonal. From these six matrices, only a few are used often. These are Square matrices, which means that the number of rows and columns are the same. On the other hand, a rectangular matrix is one that doesn't have the same number of rows and columns. In the same way, the symmetric matrix is also a square, but the triangles in the top right and bottom left corners are the same. The diagonal matrix is one in which all of the values outside of the main diagonal have zero, and the main diagonal goes from the top left to the bottom right. Last, there's an identity matrix, whose vectors don't change when you multiply them.