In general, midrange refers to computers that are more powerful and capable than personal computers but less powerful and capable than mainframe computers. (Computer power is sometimes measured in terms of millions-of-instructions-per-second - MIPS. Capability includes, for example, how many devices can be connected to and interact with the computer at the same time.) The computer industry does not define exactly what characteristics constitute "midrange."
Historically, midrange computers have been sold to small to medium-sized businesses as their main computer and to larger enterprises for branch or department-level operations. Makers of popular midrange computer lines include Hewlett-Packard, IBM, and Sun Microsystems. Today's computers are almost universally known as servers to recognize that they often "serve" applications to end users at "client" computers, that they use a client/server computing model, and, by inference (since the client/server model developed in UNIX-based operating systems), that they support standard rather than proprietary programming interfaces.