Particles called electrons are generated in an electron gun, very like the cathode ray tubes found in old tv sets. They are then accelerated up to very high speeds through a series of three particle accelerators. These are called the linear accelerator, or linac, the booster synchrotron and the large storage ring.
The storage ring is not a true circle, but a polygon, made of straight sections angled together with bending magnets. These bending magnets (also called dipole magnets) are used to steer the electrons around the ring. As the electron passes through each magnet it loses energy in the form of light. This light can then be channelled out of the storage ring wall and into the experimental stations, called beamlines.
Third generation synchrotrons like Diamond also use special arrays of magnets called insertion devices which placed in the straight sections of the ring. These cause the electrons to follow a wiggling path, which produces more intense and tuneable light.