Fundamental particles called quarks come in six different flavors. Protons are made of two up quarks and one down quark, while neutrons contain two down quarks and one up quark. A quark is a tiny particle which makes up protons and neutrons. Atoms are made of protons, neutrons and electrons.
It was once thought that all three of those were fundamental particles, which cannot be broken up into anything smaller. It was discovered, after the invention of the particle that electrons are fundamental particles, but neutrons and protons are not. Neutrons and protons are made up of quarks, which are held together by Gluons.
There are six types of quarks called flavours. The flavours are up, down, strange, charm, top, and bottom. Up, charm and top quarks have a charge of +2⁄3, while down, strange and bottom quarks have a charge of -1⁄3. Each quark has a matching antiquark. Antiquarks have a charge opposite to that of their quarks; meaning that up, charm and top antiquarks have a charge of -2⁄3 and that down, strange and bottom antiquarks have a charge of +1⁄3.