The force that keeps protons and neutrons confined inside a nucleus .

By exchanging mesons , protons keep turning into neutrons and neutrons turning into protons. This keeps the nucleons together, and the neutrons from decaying since they are always changing identity. Overall, there is always the same number of protons and neutrons: they don't just change their identity, rather they exchange identites.

The nuclear force is also called residual color force or residual strong force. This comes from the fact that only particles which are built up of color charged particles take part in the nuclear force.

About Nuclear Force in German. (Kernkraft)