The Internet is a computer network that interconnects hundreds of millions of computing devices throughout the world. Not too long ago, these computing devices were
primarily traditional desktop PCs, Linux workstations, and so-called servers that store
and transmit information such as Web pages and e-mail messages. Increasingly,
however, nontraditional Internet end systems such as laptops, smartphones, tablets,
TVs, gaming consoles, Web cams, automobiles, environmental sensing devices,
picture frames, and home electrical and security systems are being connected to the
Internet. Indeed, the term computer network is beginning to sound a bit dated, given
the many nontraditional devices that are being hooked up to the Internet. In Internet jargon, all of these devices are called hosts or end systems
