When the rays of light after getting reflected from a mirror actually meet at a point, a real image is formed.
A real image can be obtained on a screen. So, the image which can be obtained on a screen is called a real image.
A concave mirror gives a real image if the object is placed at its focal point or beyond.
When the rays of light after getting reflected from a mirror appear to meet at a point, a virtual image is formed. Such an image can only be seen through a mirror but cannot be obtained on a screen.