what is windows emulator?

an emulator is hardware or software that enables one computer system (called the host) to behave like another computer system (called the guest). An emulator typically enables the host system to run software or use peripheral devices designed for the guest system. Emulation refers to the ability of a computer program in an electronic device to emulate (or imitate) another program or device. Emulator support devices are windows,mac, Linux system's Relationship is windows and emulator to develop windows mobiles and apps