Ordinary matter is made of atoms with a massive nucleus surrounded by a cloud of electrons. The nucleus is, in turn, made of two types of particles: protons and neutrons. These are much heavier than electrons, so much so that we can pretty much assume all matter in atoms comes from them. But it doesn’t stop here: protons and neutrons are, in turn, made of smaller particles called quarks. Quarks come in six different types, each with a different charge and mass. They also have the weird property that their charge is a fraction: for example, the up quark has a charge of 2/3, whereas the down quark has a charge of -1/3. By combining up and down quarks in groups of three, we can make a proton or a neutron. For example, two up quarks and one down have a charge of 2/3 + 2/3 – 1/3 = +1 and make up a proton. One up quark and two down quarks have a charge of 2/3 – 1/3 – 1/3 and make up a neutron.
The other quarks are less common, but all of them behave as heavier versions of the up and down quarks. The charm is a heavier version of the up quark. The top is the same, but even heavier. The strange is a heavier version of the down quark, whereas the bottom quark is the heaviest of the three.