At Bessy we accelerate electrons. Normally electrons are a part of atoms, the smallest part in which material can be splitted without changing its properties. Naturally electrons circle the nucleus of an atom. At Bessy some of these electrons are used to produce synchrotron radiation. For this, electrons are grabbed from an atom and then accelerated. Standard operation of BESSY II requires roughly 12 billion (12 000 000 000) of accelerated electrons.