A force is a push or pull (repulsion or attraction) between objects.

Forces are vectors, which means they have a direction and a magnitude. You can think of them like arrows pointing in a specific direction and having a certain length. Forces can make things move, change direction, or change shape. An object that is not moving just has balanced forces - adding up all of the force vectors equals zero!

The four basic forces are the gravitational force, the electromagnetic force, the strong nuclear force, and the weak nuclear force.

The gravitational force acts between objects with mass. On a large scale, the gravitational force is what governs the motion of galaxies, stars, planets, and moons. Our weight is from the gravitational force of the Earth pulling on us. The electromagnetic force acts between objects that are charged. It combines electrostatic forces like static electricity (think of taking your hat off and your hair standing up) and the magnetic force (like a magnet pulling on a paperclip). The electromagnetic force is responsible for holding atoms together to form structures and solids.

The nuclear forces act between the fundamental protons and neutrons that make up atoms and determine which nuclei decay.