There are four such forces:

Gravitational Force
This is the binding force of the solar system and galaxies. It acts between all particles and pulls matter together.

Electromagnetic Force
This is the binding force of atoms, demonstrated when unlike charges attract. A cloud of negatively charged electrons will stay near a positively charged nucleus.

Strong Force
This is currently believed to be a remnant of a more powerful "colour force" acting on quarks inside the protons and neutrons. A nucleus, composed of positive charged protons, will not blow apart, since like charges repel, due to this force.

Weak Force
A neutron breaks up, emits an electron and becomes... a proton! This causes radioactive decay of some nuclei. When operating in this fashion, this force is 1,000 times weaker than a strong force. The higher the frequency of energy, the stronger and more electromagneticish (new word) this force becomes.

With these four forces combined, we form... um... something pretty damn cool.