If the work done by the force in displacing an object depends only on the initial and final positions of the object and not on the nature of the path followed between the initial and final position, such a force is known as conservative force.
Example:- Gravitational force is a conservative force
Work done by or against a force is said to be conservative, if the work done by the force in moving a particle along the closed path (round trip) net work done is zero.
If work done by a force in displacing an object from one position to another, depends upon the path between the two positions, such a force is known as non conservative force.
Example:- Force of friction, Viscous force and Tension force etc.
Let W₁, W₂ and W₃ denote the net work done in moving a body from A to B along three different path 1,2 and 3 respectively