We use the electromagnetic force everyday when we turn on something that uses electricity. We also have compasses that operate using the magnetic force. Electricity and Magnetism at the subatomic scale both are caused by the Electromagnetic force. The carrier of the electromagnetic force is called the photon. We know it in our big world as light. Particles with either positive or negative electric charge are affected by this force. If there is a positively charged particle, it is attracted to the negatively charged one. Two like charged particles repel each other (push each other away). The electrons in the atom are attracted to the protons in the nucleus by this force and that is what holds the atom together. Since neutrons do not have an electric charge, they are not affected by this force (they don't get to shoot photons).

Learn about the Weak Force | Learn about the Strong Force