William Stallings is a consultant, lecturer, and author of over a dozen professional reference books and textbooks on data communications and computer networking. His clients have included major corporations and government agencies in the United States and Europe. Three times he has received the Best Computer Science Textbook of the Year award from the Text and Academic Authors Association. Dr. Stallings has designed and implemented both TCP/IP-based and OSI-based protocol suites on a variety of computers and operating systems. He has a Ph.D. in computer science from the Massachusetts Institute of Technology. His cyberspace address is .