A quark and an antiquark form a meson, which is a type of subatomic particle. Mesons are composed of one quark and one antiquark, and they have a total charge of zero. Quarks and antiquarks are the fundamental particles that make up matter, and they have different charges. Quarks have a charge of either 2/3 or -1/3, while antiquarks have a charge of either -2/3 or 1/3. The combination of a quark and an antiquark creates a meson, which has a total charge of zero.