Of the four fundamental forces, we are most familiar with gravity and electromagnetism, because their efforts are most obvious in the world around us. The other two forces act only within atomic nuclei, so they are less noticeable. Gravity is the natural force of attraction that acts between objects with mass. The greater the mass of two objects, the greater the force of their mutual attraction. The farther the objects are from each other, however, the weaker is the force of gravity between them.
Gravity is the weakest of the fundamental forces, yet it has an unlimited range.
It shapes the Universe on its largest and most dramatic scales, because it acts over such vast distances throughout space. The electromagnetic force acts between all particles with an electric charge, such as electrons, protons and ions. It is the driving force in all chemical reactions, which rely on interactions between electrons in order to form molecules. The force consists of two interconnected forces, electricity and magnetism. A moving particle with an electric charge creates a magnetic field, whereas a magnetic field around a conductive substance induces charged particles to move.