What is parallax? Explain.

Parallax: When the two objects are seen on a straight line, they seem to be concident. If the objects are at different places and the eye is moved side ways then there is a relative displacement between them. The nearer object moves in the opposite direction while the further object moves in the same direction of eye.
Thus, when two objects are seen in a straight line and the eye is moved side ways when relative displacement is called parallax.