Rotational Symmetry Definition
If we can rotate a figure around a center point by less than 360 and the figure appears unchanged, then the figure has rotational symmetry.
The point around which we rotate is called the centre of rotation. And the smallest angle, when we rotate the figure is called the angle of rotation.
We can easily observe that a certain picture looks identical when it is related about a certain point at a certain degree.
A square lamina when rotated around the on-axis by 90, 180, or 270, retains its shape.