Matrix - Dimensions

The dimensions of a matrix are defined by the number of rows and columns it contains. A matrix with m rows and n columns is said to have dimensions m x n (read as “m by n”).

For example, consider the following matrix:

$$\left(\begin{array}{ccc}1& 2& 3\\ 4& 5& 6\end{array}\right)$$

This matrix has 2 rows and 3 columns, so its dimensions are 2 x 3.