UNIX and Linux System Administration Handbook, 5th Edition

13	TCP/IP Networking

It would be hard to overstate the importance of networks to modern computing, although that doesn’t seem to stop people from trying. At many sites—perhaps even the majority—web and email access are the primary uses of computers. As of 2017, internetworldstats.com estimates the Internet to have more than 3.7 billion users, or just slightly less than half of the world’s population. In North America, Internet penetration approaches 90%.

TCP/IP (Transmission Control Protocol/Internet Protocol) is the networking system that underlies the Internet. TCP/IP does not depend on any particular hardware or operating ...