This specially commissioned volume presents a unique collection of expository papers on major topics that are representative for computer science today. The 38 contributions, written by internationally leading experts in the computer science area on personal invitation, demonstrate the scope and stature of the field today and give an impression of the chief motivations and challenges for tomorrow's computer science and information technology. This anthology marks a truly extraordinary and festive moment: it is the 1000th volume published in the Lecture Notes in Computer Science series. It addresses all computer scientists and anybody interested in a representative overview of the field.