I will begin with a review of the Einstein field equations and show how their linearisation gives rise to gravitational wave solutions. The issue of gauge freedom and the analogy with electrodynamics will be discussed. I will also briefly treat gauge-invariant perturbations of black hole spacetimes. Next I will introduce the concept of conformal infinity and show how it allows for an unambiguous definition of gravitational radiation. Finally I will present some results on the numerical evolution of axisymmetric vacuum gravitational wave spacetimes.