Also known as: Green Screen, 5250 Terminal Emulation
Software running on a modern PC that displays and interacts with IBM i's traditional text-based screens, the interface most people mean by "green screen."
5250 emulation is software that lets a modern PC display and interact with IBM i's traditional character-based screens, the interface most people picture when they say "green screen." The name comes from the IBM 5250 series of physical terminals originally used to connect to AS/400 systems; today, emulation software running in a window on a normal PC does the same job over a network connection.
Many IBM i shops still run day-to-day operations partly or entirely through 5250 screens even on current Power 11 hardware. Migrating hardware doesn't require replacing this interface, though modern web-based front ends can be layered on top of the same underlying RPG/DB2 for i applications without rewriting them.