What is elastic collision?

In case of collision, if the total kinetic energy before the collision and the total kinetic energy after the collision between the objects participating in the collision are equal, then the collision is called an elastic collision. For example, if we say, two cars moving with the kinetic energy of 100 joules and 150 joules collide.
Now after the collision, their kinetic energies are 130 joules and 120 joules. Here the total kinetic energy before the collision is 250 joules and the energy after the collision is 250 joules. Since kinetic energy is conserved between them, we call this collision an elastic collision.