According to the law of conservation of energy, the total energy of a body remains constant in a closed system. Kinetic energy refers to the energy possessed by a body due to its motion, which means that there will be a collision between the objects, and kinetic energy can be transferred from one object to another.
Two types of collision are elastic and inelastic collision. In elastic collision, when the objects collide with each other, the sum of the kinetic energy of both objects remains constant, proving that kinetic energy is conserved throughout the whole process. In an inelastic collision, the kinetic energy is not conserved; when the two objects collide with each other, some of the kinetic energy is transformed into another energy, such as heat energy, light energy, or sound energy. So, in short, kinetic energy is not conserved, but in an ideal situation like a perfectly elastic collision, kinetic energy can be conserved.