All the objects from everyday life that we can bump into, touch or squeeze are composed of atoms. This atomic matter is in turn made up of interacting subatomic particles—usually a nucleus of protons and neutrons, and a cloud of orbiting electrons. Typically, science considers these composite particles matter because they have both rest mass and <answer>volume</answer>. By contrast, massless particles, such as photons, are not considered matter, because they have neither rest mass nor <answer>volume</answer>. However, not all particles with rest mass have a classical <answer>volume</answer>, since fundamental particles such as quarks and leptons (sometimes equated with matter) are considered "point particles" with no effective size or <answer>volume</answer>. Nevertheless, quarks and leptons together make up "ordinary matter", and their interactions contribute to the effective <answer>volume</answer> of the composite particles that make up ordinary matter.
Despite not having size or volume themselves, quarks and leptons contribute to what measure of composite particles in matter?
volume