D-mesons are subatomic particles made up of a charm quark and an anti-up or anti-down quark. They are part of the meson family, which consists of quark-antiquark pairs. D-mesons come in several varieties, including D⁰, D⁺, and D⁻, each differing in their specific quark composition and charge. These particles play a crucial 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 particularly important in exploring CP violation, which has implications for the matter-antimatter asymmetry in the universe.