A physical thin client is a small, simple device that allows you to connect to a virtual desktop environment. It has the ability to connect to a monitor, speakers, input devices, and sometimes an external storage device for the purpose of uploading new information to the centralized server.
Hardware thin clients are often extremely cheap compared to full-fledged desktop computers (referred to as fat clients). These systems can range in size from a typical workstation to as small as an external hard drive. Ultra-thin clients are even smaller as they require virtually no local storage to initialize the networking protocols and establish a link to the host.
Thin clients can be installed on existing machines as well. This allows IT departments to extend the life of its inventory significantly while reducing the overhead costs for new systems. Just imagine the cost reduction of replacing 50 traditional stand-alone workstations with 50 thin clients running on a centralized server. The thin client hardware, IT support overhead, and licensing costs are all reduced significantly in the long-term.