If a figure is a square then it is a regular, quadrilateral . is this true or false ? explain.

This is a regular quadrilateral  because it has 4 congruent sides and 4 congruent right angles

In geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90-degree angles, or right angles). It can also be defined as a rectangle in which two adjacent sides have equal length.