In the nuclei atoms we know that there are 2 type of particles named protons and neutrons.As we know that the neutrons are uncharged and protons are positively charged thus in such a close proximity when the proton's are just touching each other the electrostatic forces of repulsion between the particles becomes exceedingly large thus rendering the nucleus theoretically unstable. But as we know that the nucleus is inherently stable indicating that there is another type of force that must act between the nucleons (proton's and neutrons) this fundamental force is known as strong nuclear force and is the strongest force among the 4 fundamental forces in nature.
