Gravity is the force of attraction between objects and is considered as one of the four fundamental forces of nature; the others are electromagnetism, which encompasses magnetic forces created by electricity, and the strong and weak nuclear forces that hold atoms together. As a rule, gravity acts between all matter in the universe and cannot be turned off, blocked or modified, but it can be counteracted with an opposing force. Thus it is considered as a universal force and affects the smallest or largest of objects. Gravitation is the force that keeps us on Earth, the Earth around the Sun and the solar system around the center of the universe. Even so, gravitation or gravity is by far the weakest of the forces and as such, is not important in the interactions between atoms and molecules. Its major importance concerns the very large objects such as planets and large distances that separate these masses.