Massless virtual gluons compose the overwhelming majority of particles inside hadrons, as well as the major constituents of its mass (with the exception of the heavy charm and bottom quarks ; the top quark vanishes before it has time to bind into a hadron). The strength of the strong force gluons which bind the quarks together has sufficient energy (E) to have resonances composed of massive (m) quarks (E ≥ mc). One outcome is that short-lived pairs of virtual quarks and antiquarks are continually forming and vanishing again inside a hadron. Because the virtual quarks are not stable wave packets (quanta), but an irregular and transient phenomenon, it is not meaningful to ask which quark is real and which virtual; only the small excess is apparent from the outside in the form of a hadron. Therefore, when a hadron or anti-hadron is stated to consist of (typically) 2 or 3 quarks, this technically refers to the constant excess of quarks vs. antiquarks.