Square Matrix :
     Any matrix that has equal number of rows and columns is called square matrix. E.g: 2x2, 3x3 matrix.

2x2 Square Matrix		3x3 Square Matrix
a11 a12 a21 a22 2 rows & 2 columns		b11 b12 b13 b21 b22 b23 b31 b32 b33 3 rows & 3 columns

Diagonal Matrix :
     A Diagonal matrix is a square matrix with numbers on the leading diagonal and zeros in all other places.

Diagonal Matrix

2 0 0 0 3 0 0 0 8

Identity Matrix :
     An identity matrix is a square matrix denoted as I. It has ones (1) down the leading diagonal and zeros in all other places.

2x2 identity		3x3 identity
1 0 0 1		1 0 0 0 1 0 0 0 1

Note: Any matrix multiplied by its identity matrix leaves the matrix unchanged.
It is similar to multiplying a number by 1.

2 2 5 3

x

1 0 0 1

=

2 2 5 3

Zero (Null) Matrix :
      A zero or null matrix is a matrix with 0 as the element for all its cells (rows and columns).

Zero (null) Matrix

0 0 0 0 0 0 0 0 0

Symmetric Matrix :
      A symmetric matrix is a matrix where a_ij = a_ji. i.e an element at the i^th row, j^th columns should be equal to the element at the j^th row, i^th columns.

Symmetric Matrix

1 2 3 2 4 5 3 5 6

Equality Matrix :
     For any two matrices to be said as equal matrices they should be of same size and have same values.