Chirality

A chiral molecule is a type of molecule that
lacks an internal plane of symmetry and has a non-superimposable mirror image.
The feature that is most often the cause of chirality in molecules is the
presence of an asymmetric carbon atom.

The term chiral in general is used to describe an
object that is non-superposable on its mirror image. Achiral (not chiral)
objects are objects that are identical to their mirror image.

Ex:-Human hands are the most universally
recognized example of chirality. The left hand is a non-superposable mirror
image of the right hand; no matter how the two hands are oriented, it is
impossible for all the major features of both hands to coincide.