The upsilon meson is a type of subatomic particle known as a meson, which is made up of a quark and an antiquark. Specifically, the upsilon meson consists of a bottom quark and its corresponding antiquark. It is part of the quark model and is classified as a heavy meson due to its relatively large mass compared to other mesons. Discovered in 1977 at the Fermilab particle accelerator, the upsilon meson plays a significant role in the study of quantum chromodynamics (QCD), the theory that describes the strong force interactions between quarks and gluons. Its properties help physicists understand the behavior of matter at a fundamental level.