A square is a special rectangular that its length equals its width. When we are prompted to specify other corner point after specifying the first corner point, we can enter @a numeric value for the length, same numeric value for the width or we can use Dimension option.  

Use POL command will allow us to create a square. Just enter POL and press Enter key, when prompted to enter the number of sides, just press Enter because the default number of sides is 4.

By default, after specifying the number of sides, we are prompted to specify the center or edge of polygon, but here we need to specify the edge of the square so we can draw a square by specifying two endpoints, as shown in the following picture,