A rectangular matrix is a two-dimensional array of numbers arranged in rows and columns, where the number of rows is not equal to the number of columns. For example, a matrix with 3 rows and 4 columns is rectangular. Rectangular matrices can be used in various mathematical applications, including solving systems of equations and representing data. In contrast to a square matrix, where the number of rows equals the number of columns, rectangular matrices can have different dimensions. They are often denoted by their size, such as m x n, where m represents the number of rows and n represents the number of columns.