We recall that there are six different quarks that are grouped in three families. Each quark also has a corresponding antiquark (e.g., the anti-up-quark anti-u). The antiquarks have the same mass and lifetime as the corresponding quark, but they all have an electrical charge of the opposite sign.
All these quarks interact with each other through the strong interaction. Quarks are combined together into particles called hadrons (Greek hadros = strong). The name comes from the fact that the strong interaction is used when hadrons interact with each other.
Hadrons are divided into two groups of particles. Particles built up of three quarks (or three antiquarks) are called baryons (Greek baros = heavy). Particles built up of two quarks (one quark and one antiquark) are called mesons (Greek mesos = medium/middle).
There are no hadrons consisting of a single quark, and at the present we have no evidence of hadrons containing more than three quarks. The quarks in the first family build up the atomic nuclei in the universe. The four remaining quarks (and their antiquarks) are used as building blocks for short-lived particles that do exist in our natural environment. But they existed in great numbers at the birth of the universe and they are recreated at physics experiments with high energy particle collisions.