Quarks are considered to be elementary particles, meaning they are not thought to have any substructure or be composed of smaller particles. According to our current understanding in particle physics, quarks are indeed among the fundamental building blocks of matter.
Quarks are point-like particles that possess a property called "color charge" and are affected by the strong nuclear force. They are always found in combinations to form composite particles called hadrons, such as protons and neutrons. Quarks come in six flavors: up, down, charm, strange, top, and bottom. Each flavor carries a fractional electric charge, with up and top quarks having a positive charge, while down, strange, charm, and bottom quarks have a negative charge.
However, it's important to note that while quarks are considered elementary, our understanding of particle physics is continuously evolving. New experimental observations and theoretical advancements may lead to refinements or revisions of our current understanding in the future. Researchers are actively exploring the nature of fundamental particles through experiments conducted at particle accelerators like the Large Hadron Collider (LHC) to further probe the subatomic realm.