I did some research on Wikipedia, and I quote from the write up on Real Particles: "The term(Virtual Particles) is somewhat loose and vaguely defined, in that it refers to the view that the world is made up of "real particles": it is not; rather, "real particles" are better understood to be excitations of the underlying quantum fields. Virtual particles are also excitations of the underlying fields, but are "temporary" in the sense that they appear in calculations of interactions, but never as asymptotic states or indices to the scattering matrix." What I wanted to ask was, what is the meaning of "excitation of the underlying fields"? What quantum field are they talking about? I always thought that in quantum mechanics fields were basically made up of particles. But that brings me back in a loop.