What are conservative force,non-conservative force,conservative field,and non-conservative field?

(N/A) Conservative force: $A$ force is said to be conservative if the work done by the force on a body is path-independent and depends only on the initial and final positions. Such a field is known as a conservative field.
For example,gravitational force,electrostatic force,and magnetic force.
Non-conservative force: $A$ force is said to be non-conservative if the work done by the force on a body is path-dependent. The work done by such a force in moving a body around a closed path is not zero. Such a field is known as a non-conservative field.
For example,frictional force and viscous force.