conservative and non-conservative forces

conserve means what work is done it is not shown externally, it means suppose an object projects upwards with some velocity, in its path its kinetic energy changes, but whenever it reaches to the ground it kinetic energy is same as when it projects.
Therefore the applied force here is conservative.
we take an ideal spring, it is exerted by some force, then with same force again it gets stretched to get original shape. Here the force is elastic force.
Here the important point to remember is that the work done by the conservative force depends only upon the points on which the force applied but not on the path followed by the force.
In case non-conservative force, the work done by the force depends upon the points of locations of the force and also path followed by the force.
For example, the frictional force and electromagnetic induction are the examples of non-conservative forces. Once, frictional force applies on the object, then it can't be regained, i.e., that force is dissipated, only through applied force on the object.
Here one important point is to remember is that work-energy theorem is applicable for conservative force only but not for non-conservative forces because the path followed by the non-conservative forces, kinetic energy of the object varied periodically up and down, so it is difficult to find out the change in kinetic energy.