In this section we consider the processes which lead from the Big Bang to the formation of stars and galaxies. A principle which will become clear is that more complex objects are progressively built from simple starting materials. This is also true in the next section of this module on Planetary Formation. Thus during the Big Bang the 'seeds' of matter were created. These eventually combined to form the most primitive of all the chemical elements — hydrogen (chemical symbol H). In this section we shall consider, amongst other issues, how the heavier elements were constructed from the hydrogen atoms which formed close to the beginning of time.