What is free energy? Tesla wanted free electricity.
Free energy is not an official scientific concept and therefore not easy to define. It is often identified with energy whose source is the mythical perpetual motion machine, which is simply a machine that is capable of producing as much or more energy than was necessary to make it run. However, free energy sometimes refers to any natural force that manifests itself on Earth without human intervention - magnetism, gravity, lightning, but in fact it also includes solar radiation, wind or water energy, i.e. the renewable sources commonly used today.
Perhaps this is why free energy is often also understood in the sense of some as yet undiscovered energy source that, by its very nature, no one will be able to appropriate. This is why the subject of free energy has come to the forefront of conspiracy theorists' minds, who believe that powerful circles of energy and oil tycoons are persistently blocking research in this area to preserve their fat profits.