This comprehensive book by Wissam Ahmed Abdel Aziz delves into the profound concepts of both special and general relativity. Published by Dar Safa for Publishing and Distribution in 2004, it systematically explores Einstein's revolutionary ideas. The text begins with the principles of special relativity, covering time dilation, length contraction, and the iconic equation E=mc². It then progresses to the intricate framework of general relativity, lucidly explaining how gravity arises from the curvature of spacetime. This work is an indispensable resource for physics students and enthusiasts seeking a clear understanding of the universe's fundamental laws.