A conservative force is a force that conserves mechanical energy, where the work done by that force on an object moving between 2 points is independent of the path taken. That's a pretty unclear definition, so suffice to say that in basic mechanics, gravity forces and spring forces are conservative forces, and every other type force (friction, tension, applied forces, other contact forces, etc.) are non conservative forces.
Your explanation is basically the same as what my book says.. If I am not mistaken my instructor used to say that we can convert back the energy produced/lost by conservative forces but not in non-conservative forces. Is this right?
We say that gravety is a conservative field, because there IS independence of path.
the potential energy of an object is mgh, mass X gravitational constant X height above ground. It does NOT matter how the object got there the result is the same.
As the object moves through this field(gravity in this example) sometimes the force works
AGAINST the object, and sometimes the force helps the object (downhill) but if we move in a closed path, the net result is zero. We did NOT profit, and we did not loose anything,
we BROKE EVEN (in layman's terms)