1) A workstation is a computer intended for individual use that is faster and more capable than a personal computer. It's intended for business or professional use (rather than home or recreational use). Workstations and applications designed for them are used by small engineering companies, architects, graphic designers, and any organization, department, or individual that requires a faster microprocessor, a large amount of random access memory (RAM), and special features such as high-speed graphics adapters. Historically, the workstation developed technologically about the same time and for the same audience as the UNIX operating system, which is often used as the workstation operating system. Among the most successful makers of this kind of workstation are Sun Microsystems, Hewlett-Packard, DEC, and IBM.
2) In IBM and other corporations, the term "workstation" is sometimes used to mean "any individual personal computer location hooked up to a mainframe computer." In today's corporate environments, many workers have such workstations. They're simply personal computers attached to a local area network (LAN) that in turn shares the resources of one or more large computers. Since they are PCs, they can also be used independently of the mainframe assuming they have their own applications installed and their own hard disk storage. This use of the term "workstation" (in IBM, sometimes called a "programmable workstation") made a distinction between the earlier "terminal" or "display terminal" (or "dumb terminal") of which the 3270 Information Display System is an example.