- Nuclear forces are strongly attractive at typical inter-nucleon distances within the nucleus (around 0.8 fm to a few fm). - However, they become strongly repulsive at very short distances (less than about 0.8 fm), preventing the collapse of the nucleus. - They are the strongest fundamental forces in nature over their very short range. - They are largely charge-independent, acting equally between proton-proton, neutron-neutron, and proton-neutron pairs. - The fact that they are both attractive and repulsive depending on the separation distance between nucleons is a key characteristic.