A picture of a neutron. The 'u' stands for an up quark, and the 'd' stands for a down quark.
Neutrons, with protons and electrons, make up an atom. Neutrons and protons are found in the nucleus of an atom. Unlike protons, which have a positive charge, or electrons, which have a negative charge, neutrons have zero charge which means they are neutral particles. Neutrons bind with protons with the residual strong force.