Energy can be transferred from one store into another - as one store empties, another store fills. The process by which this happens is called the pathway. There are four main pathways:
Energy can remain in the same store for millions of years or sometimes just for a fraction of a second. There are energy transfers going on all the time - whenever a system changes there is a change in the way some or all of the energy is stored.
A swinging pirate ship ride at a theme park
A car driver braking in an emergency - kinetic energy is transferred into thermal energy of the surroundings by the work done by the force of friction on the brakes.
A snowball hitting a wall - kinetic energy is transferred into thermal energy of the surroundings by the work done by the force from the wall.