At this point, it should be noted that the only "things" that actually exist for science are in fact systems, such as those just mentioned. Accordingly, asking science "What kinds of things exist?" is tantamount to asking "What kinds of systems are there?" And the final answer that physics gives us to this question is this: the fundamental systems are what are force fields and their quanta. A quantum, then is a particle that represents the force as a point-particle, whereas a field represents the force as space, allowing for a wave interpretation. In this well-known Wave/Particle Duality, the quantum as a particle is discreet and localized; whereas a quantum as represented by the so-called wave-packet is continuous and diffused, perhpas throughout all of Space-Time. In fact, even Space-Time itself turns out to be the field of one of the fundamental forces carrying particles, for curved Space-Time is none other than the Gravitational Field itself, and its (as yet merely theoretical) quantum is called the Graviton. All told, there are four fundamental Quantized Fields: the Gravitational Field; the Electromagnetic Field, with its Photon as Quantum; the Strong Nuclear Field, with the Meson as Quantum; and the Weak Nuclear Field, with its so-called Intermediate Vector Bosons as Quanta. These four force fields either are or bind together the smallest and biggest systems in the World.