Fifty years of X-ray astronomy: A look back and into the (near) future

In this article we review the history of X-ray astronomy from the pioneering years to the age of the great observatories. We will try to show how new discoveries have been linked to technological breakthroughs, to science policy achievements and have been always supported by the passion of scientists who dedicated their life to the exploration of the Universe at the high energies. We will also briefly review the current challenges of X-ray astronomy (and astrophysics) and the missions already planned or that are being designed to address these challenges.