Mesons are a category of subatomic particles that consist of a quark and an antiquark. They are classified as bosons due to their integer spin and are characterized by their short lifespans, typically decaying within a few nanoseconds. The existence of mesons was first predicted by the physicist Hideki Yukawa in 1935, and they were experimentally confirmed in 1947.

In the realm of particle physics, mesons are significant because they act as mediators of the strong nuclear force, which binds protons and neutrons within atomic nuclei. Specifically, mesons are responsible for the residual strong force—this is the force that holds nucleons together after the exchange of gluons has occurred.

There is a diverse array of mesons, each exhibiting unique properties. For instance, the pion ($\pi$) is the lightest meson and is primarily responsible for mediating the strong nuclear force. The kaon ($K$), another notable meson, holds particular significance in particle physics as it was the first particle observed to exhibit CP violation, which refers to the violation of the combined symmetry of charge conjugation ($C$) and parity ($P$).

In summary, mesons represent a vital class of subatomic particles that significantly enhance our understanding of the fundamental forces of nature.