DOUGLAS COMER is a professor at Purdue University where he teaches popular computer networking courses. He also teaches hundreds of professionals and diverse audiences around the world each year about he Internet. He has written a widely acclaimed and extremely popular series of books on networking and the Internet. He was one of the researchers who contributed to the formation of the Internet in the late 1970s and 1980s. He has served on the Internet Architecture Board, the group responsible for guiding development of the Internet, and is a Fellow of the ACM. He wrote this book in response to everyone who has asked him for an explanation of the Internet that is both technically correct and easily understood.