An execution mode supported by the Intel 80286 and later processors. In real mode, these processors imitate the Intel 8088 and 8086 microprocessors, although they run much faster. The other mode available is called protected mode. In protected mode, programs can access extended memory and virtual memory. Protected mode also supports multitasking. The 80386 and later microprocessors support a third mode called virtual 8086 mode. In virtual mode, these microprocessors can run several real-mode programs at once.
The DOS operating system was not designed to take advantage of protected mode, so it always executes programs in real mode unless a protected mode extender is run first.