An refers to any software or mobile application designed to communicate with a vehicle’s Engine Control Unit (ECU) via an ELM327-based OBDII adapter. These programs bridge the gap between your car's complex diagnostic protocols and standard devices like smartphones or PCs. Popular ELM327 Programs by Platform
The choice of program often depends on your operating system and diagnostic needs: cdn.sparkfun.com ELM327 OBD to RS232 Interpreter - Sparkfun elm 327 program