I am trying to teach myself physics this summer and have just come across Eistein's e=mc2 formula. This gives a correlation between energy and mass, and that when energy is imparted to an object the object will gain mass, and in the presence of gravity weight. Does this mean that energy has an inherent mass, or does it mean that when energy is transferred part of the energy lost has simply been transformed into mass? If it is the latter then what form does said mass take?

P.S.- I very much doubt that energy has inherent mass but one never knows...

I'm still waiting for someone to answer