Many of the modern ideas in cosmology can be explained without the need
to discuss General Relativity. The present chapter represents an attempt to do this based entirely on Newtonian mechanics. The equations describing
the velocity (called the Friedmann equation) and acceleration of the universe are derived from Newtonian mechanics and also the cosmological constant is introduced within a Newtonian framework. The equations of state are also derived in a very simple way. Applications such as conservation laws, the age of the universe and the inflation, radiation and matter dominated epochs are discussed.