Quarks are elementary particles that are considered to be fundamental constituents of matter. According to our current understanding in particle physics, quarks are believed to have mass. However, it's important to note that the concept of mass in particle physics can be somewhat subtle.
In the Standard Model of particle physics, which is the prevailing theory that describes the fundamental particles and their interactions, quarks are treated as point-like particles with no internal structure. This means that they are not thought to be made up of smaller components.
The masses of quarks are typically described in terms of their energy, thanks to the famous mass-energy equivalence relationship expressed by Einstein's equation, E = mc^2. Quarks possess energy due to their interactions with the Higgs field, which is responsible for giving particles their mass. The more strongly a quark interacts with the Higgs field, the greater its mass is considered to be.
Quark masses are typically expressed in terms of their relative masses compared to each other. The up quark and down quark, which are the lightest of the quarks, are often assigned masses close to zero in many calculations. However, the other quarks, such as the strange, charm, top, and bottom quarks, have significantly larger masses. For example, the top quark is the heaviest known elementary particle, with a mass around 180 times that of the proton.
It's worth mentioning that the study of quark masses is an active area of research, and precise measurements of their masses are subject to refinement as experimental techniques improve.