Sim is short for simulation or simulator, used to describe digital modelling that recreates the sound and behaviour of real audio equipment. In guitar and audio gear, sims commonly emulate amplifiers, speaker cabinets, microphones, rooms, or entire signal chains.

Sims are widely used in pedals, processors, recording interfaces, and software, allowing players to achieve realistic tones without using physical amps or cabinets. They are valued for consistency, convenience, and flexibility, especially in home recording, silent practice, and live setups that rely on direct connections to PA systems.