The top quark is one of the six types of quarks, which are fundamental particles that make up protons and neutrons. It is the heaviest of all quarks, with a mass about 173 times that of a proton. The top quark plays a crucial role in the Standard Model of particle physics, helping to explain the interactions between particles. Discovered in 1995 at the Fermilab collider, the top quark is unique because it decays very quickly, making it challenging to study. Its existence helps scientists understand the forces that govern the universe and the behavior of matter at the smallest scales.