Book excerpt: The year 2005, which marked the 100th anniversary of the 'annus mirabilis', the year in which Albert Einstein published three of his most important scientific papers, was the perfect opportunity to review and to present the current scientific understanding of relativistic topics. This book provides an up-to-date reference on the theory of gravity, relativistic astrophysics and cosmology. It is a useful reference tool for both the expert and the new-comer in these fields.