  The Square Kilometre Array (SKA) is called to revolutionise essentially all
areas of Astrophysics. With a collecting area of about a square kilometre, the
SKA will be a transformational instrument, and its scientific potential will go
beyond the interests of astronomers. Its technological challenges and huge cost
requires a multinational effort, and Europe has recognised this by putting the
SKA on the roadmap of the European Strategy Forum for Research Infrastructures
(ESFRI). The Spanish SKA White Book is the result of the coordinated effort of
120 astronomers from 40 different research centers. The book shows the enormous
scientific interest of the Spanish astronomical community in the SKA and
warrants an optimum scientific exploitation of the SKA by Spanish researchers,
if Spain enters the SKA project.
