The Square Kilometre Array (SKA) is being designed as the most powerful facility for radio astronomy ever conceived. Consisting of two separate telescopes on two continents (Australia and South Africa) a frequency range of 50 MHz to approximately 14 GHz will be covered, allowing a wide range of astrophysics to be covered. In this seminar, I will briefly introduce the SKA project and describe the instrumentation. I will briefly summarise the broad SKA science case, before focusing on a few areas of high scientific impact, including the Epoch of Reionisation (EoR), cosmology, and high energy astrophysics. In particular, I will attempt to demonstrate the unique contributions that the SKA can make in these areas, alongside other existing and future facilities such as Planck, JWST, E-ELT, Euclid, and the CTA. In particular, to unravel the early stages of galaxy and mass assembly and pin down cosmological evolution, during the EoR and earlier/later, a multi-wavelength approach is required to separate the astrophysics and the cosmology. Organisations that span and harness these facilities and capabilities will be at the forefront of modern astrophysics and cosmology. I propose that INAF is one such organisation. Italy has played a leading role in the definition of the SKA science case, plays an important role in the technical development of the SKA, and has a footprint in almost all the major future astrophysics and cosmology facilities.