Laws of reflection :
The reflection of light from a surface obeys certain laws called laws of reflection. They are :

(i)  The angle of incidence is equal to the angle of reflection. i.e., i = r.
(ii)  The incident ray, the reflected ray and the normal at the point of incident, all lie in the same plane.

The laws of reflection are applied for all type of reflections.
Ex.1    Calculate the angle of reflection.

Sol.    According to the law of reflection, incident angle equal to reflected angle. So angle of reflection r = 50°.

Mirror :
It is a highly polished surface, which is quite smooth and capable of reflecting a good fraction of light from its surface. 
(a) object :
Anything which gives out light rays (either its own or reflected) is called an object.

(b) Image : 
The reproduction of object formed by mirror or lens is called an image. 

Difference between image and shadow