A rotation is what occurs when we turn an object or shape around a central point. The object is exactly the same shape and size, just rotated around (like going in a circle). Every point on the object or shape has a corresponding point on the image.
Commonly we describe rotations using a degree measure, and as being either clockwise or anticlockwise.
Particularly at the moment you need to be able to identify rotations of:
$90^\circ$90°, $180^\circ$180°, $270^\circ$270° and $360^\circ$360° in both clockwise and anticlockwise directions.
Have a play with this interactive. Here you can change the shape that of the object and the position of the central rotation point. Notice how a rotation of $360^\circ$360° takes you right back to where you started.
Here are some worked examples.
Which of the following figures represents the given flag after rotating it anticlockwise around the red point by 90° ?
Which is the correct image after the original is rotated by $45^\circ$45° clockwise?
What is the clockwise angle of rotation of the original image about point $O$O?