Gravitons

Gravitons are particles which are thought to exist which would represent the conventional theories answer to the ultimate cause (or source) of gravity. The graviton would be to gravity as the photon would be to light (or any electromagnetic radiation, at any frequency).

By conventional theories, the graviton would be the carrier of the gravitational force. When masses interchanged gravitons, in something like a mad baseball game of catch and relay, the gravitational force would appear as a result.

The interactions would take place in somewhat the same manner as interactions take place for the other forces of nature. For electromagnetic interactions, the photon is used. For the strong and weak forces, the Vector boson is used as the carrier particle.