D mesons are subatomic particles that contain a charm quark and an anti-up or anti-down quark. They are part of the family of particles known as mesons, which are made up of a quark and an antiquark. D mesons come in several varieties, including D⁰, D⁺, and D⁻, each differing in their quark composition and charge. These particles play a significant role in the study of particle physics and quantum chromodynamics, helping scientists understand the interactions between quarks and the fundamental forces of nature. D mesons are often produced in high-energy collisions, such as those occurring in particle accelerators like the Large Hadron Collider.