Short answers, pulled from the story.
The strong interaction, also called the strong force or strong nuclear force, is one of the four known fundamental interactions. It confines quarks into protons, neutrons, and other hadrons, and it binds protons and neutrons together to form atomic nuclei.
At a range of 10 to the minus 15 meters, the strong force is about 100 times as strong as electromagnetism. It is roughly a million times as strong as the weak interaction and about 10 to the 38th power as strong as gravitation.
Quarks cannot be isolated because of color confinement. The strong force between quarks does not diminish with distance, so pulling two quarks apart adds enough energy to create new quark-antiparticle pairs, leaving only hadrons observable and never free quarks.
The gluon carries the strong interaction. It is a massless gauge boson that, unlike the electrically neutral photon, itself carries color charge, which comes in three types: red, green, and blue.
The strong force binds quarks together inside hadrons through gluons at distances under about 0.8 femtometers. The nuclear force, or residual strong force, is a leftover of that force carried by mesons that binds protons and neutrons into a nucleus, and unlike the strong force it diminishes rapidly with distance.
In 1964 Murray Gell-Mann, and independently George Zweig, proposed that baryons and mesons were composed of elementary particles. Zweig called them aces and Gell-Mann called them quarks, and the theory became known as the quark model.
The strong interaction stores potential energy in the nuclear force, producing a mass defect, and differences between mass defects power nuclear fusion and nuclear fission. Fusion accounts for most energy production in the Sun and other stars, while fission drives the decay of radioactive elements and isotopes.