The kinds of SPHERICAL MIRRORS are :
(i) CONCAVE MIRROR
(ii) CONVEX MIRROR
IN CONCAVE MIRROR: the Silvered surface is away from a center of curvature and the focal length is negative, i.e. reflecting surface is towards a center of curvature.
IN CONVEX MIRROR: the Silvered surface is towards the center of curvature and the focal length is positive i.e. reflecting surface is away from the center of curvature. It always forms diminished (small) image which is VIRTUAL.