In addition to the standard interface seen in terminals and terminal emulators, ISPF can be run from a workstation using the display functions of your workstation operating system. In the ISPF library this is called running in GUI mode.
The ability to run in GUI mode is provided via the ISPF Client/Server component, also known as the ISPF Workstation Agent (WSA). The WSA is an application that runs on your local workstation and maintains a connection between the workstation and the ISPF host. The WSA also allows you to edit host data on your workstation and workstation data on the host. In ISPF this is called distributed editing. For more information about distributed editing, see the 'Download Data Set to Workstation Utility (Option 3.7)' section of the z/OS V2R2 ISPF User's Guide Vol II.