Step 1: Recall image formation in spherical mirrors.
In spherical mirrors, images can be formed either on the same side as the object or on the opposite side depending on the nature of the mirror and object position.
Step 2: Image on the same side as object.
When the image is formed on the same side as the object (as in concave mirror for certain positions), the image is real.
Step 3: Image on the opposite side of object.
When the image is formed behind the mirror (opposite side of object), the image is virtual.
Step 4: Conclusion.
Thus, images formed on the side of the object are real, and those formed on the opposite side are virtual.