Some people raised their eyebrows when I told them that I was writing a book on congestion control, and said, ‘Is this topic really large enough for a book?’ Well, it certainly is, and I am sure that it is needed. For example, there are quite a number of . students out there who work in this field–yet, when they start out, they do not have a comprehensive introductory book about the subject. This book is for them and, of course, for anyone else with an interest in this fascinating topic–graduate students, teachers in academia and network administrators alike.