There are four distinct fundamental forces in nature: gravitational force, electromagnetic force (EMF), the strong nuclear force (SNF), and the weak nuclear force (WNF). The weak nuclear force causes nuclear radiation (i.e., the radioactive decay of atoms). The strong nuclear force, an attractive force, holds protons and neutrons together; the electromagnetic force attracts particles with opposite charges and repels those with the same charge. The SNF operates at a short range, and the EMF operates at all distances.
