How does matter and energy are conserved?

One sort of energy is transformed to another, so that energy is never destroyed, it just keeps changing its form. Matter can also be changed into energy, so any given piece of matter can continue to exist in one form or another. For example, if you create appropriate conditions across a wire, the electrons in the wire will acquire the kinetic energy to move along the wire, this creates electricity, the electricity can then generate heat on a stove, and water in a pot can absorb this heat to boil. Electrons moving, heat, and water changing to steam all involve using the same energy. As an example involving mass, one can put a certain amount of fuel in a rocket, and its mass will decrease as the rocket burns the fuel in a chemical reaction in order to take off and fly.