We briefly review some models of dark energy. We start with the cosmological constant including models arising in string theory, before discussing dynamical models where a scalar field may be responsible for the observed late time acceleration. The possibility that we are not fully in control of the gravity sector is discussed and the possibility that the acceleration may be some manifestation of modified gravity on large scales is shown. All cases require some degree of fine tuning for the models to be compatible with observation. Finally, we briefly discuss some recent fun work involving scalar-tensor theories of gravity in which a self-tuning mechanism exists leading to the same late time cosmology independently of the size of the cosmological constant. Solutions include having radiation and matter dominated like regimes whilst the energy density remains dominated by a cosmological constant.