Jacob Bekenstein, an Israeli physicist of the Hebrew University, Jerusalem, planted the seeds of a revolution of our understanding of space-time. Using conservative intuitive methods including time-old gedanken experiments, he discovered that black holes have thermodynamical properties such as entropy.Moreover, he found that their entropy was not extensive, unlike that of any other thermodynamical system considered before, but rather is proportional to the surface of their horizon. Furthermore, Bekenstein pioneered the study of black holes by focusing on their information content aspects. This led him to obtain bounds of a holographic nature on the amount of information that can be stored in a given region of space-time.This book contains a series of scientific and personal contributions by his contemporaries who recall the struggle against his ideas and then with them: the fate accompanying many revolutionary ideas. This is followed by original scientific contributions by many of the leaders of current research on black hole physics and holography. They have trodden his path and expanded it. The impact of Jacob Bekenstein’s visionary ideas is just starting to be understood.