In physics, a fundamental force or interaction is an irreducible, or base-level mechanism that cannot be explained by recourse to a deeper level of physical entity.
Successively higher levels of particles and interaction originate within the fundamental forces. Such fundamental forces are the bottom-line of explanatory regressions. The currently recognized fundamental forces are weak and strong interactions, electromagnetic force, and gravitational interaction.
The modern quantum mechanical view of weak, strong, and electromagnetic postulates that the elementary particles of matter, protons and electrons (fermions) do not interact directly with each other. Instead, they are carry a charge and are postulated to exchange virtual particles (gauge bosons), which are the interaction carriers or force mediators of the fundamental forces of Nature. Photons mediate the interaction of electric charges; and gluons mediate the interaction of color charges.
The fortuitous values of the fundamental constants are evoked in the teleological, anthropic apologetic argument.