Although UUCP may be a reasonable choice for low-cost dial-up network links, there are many situations in which its store-and-forward technique proves too inflexible, for example in Local Area Networks (LANs). These are usually made up of a small number of machines located in the same building, or even on the same floor, that are interconnected to provide a homogeneous working environment. Typically, you would want to share files between these hosts, or run distributed applications on different machines.
These tasks require a completely different approach to networking. Instead of forwarding entire files along with a job description, all data is broken up in smaller chunks (packets), which are forwarded immediately to the destination host, where they are reassembled. This type of network is called a packet-switched network. Among other things, this allows to run interactive applications over the network. The cost of this is, of course, a greatly increased complexity in software.
The solution that system -- and many non- sites -- have adopted is known as TCP/IP. In this section, we will have a look at its underlying concepts.