Quarks are considered to be elementary particles, which means they are not composed of smaller particles. As far as our current understanding goes, quarks are fundamental, indivisible constituents of matter.
Regarding the size of quarks, it's important to note that quarks do not have a defined size in the same way that macroscopic objects do. In particle physics, the concept of size becomes more subtle at the subatomic level. Quarks are often treated as point-like particles, meaning they are considered to be dimensionless, without any internal structure or size.
However, it's important to clarify that the term "size" can have different interpretations depending on the context. In some cases, the term "size" may refer to the region of space where the influence of a particle is significant. For example, in high-energy particle collisions, the quarks' interactions can occur over a limited spatial extent.
Quarks are characterized by their various properties, such as mass, electric charge, and color charge. They come in six different flavors: up, down, charm, strange, top, and bottom. These flavors have different masses and electric charges, but they all share the property of carrying fractional electric charges, either +2/3 or -1/3 of the elementary charge.
To summarize, quarks are considered to be elementary particles, and our current understanding suggests that they do not have a defined size or internal structure. They are fundamental constituents of matter, and our description of their properties focuses on attributes such as mass, charge, and flavor.