What enables applications to be run on Apple silicon macs that were originally built for...

Rosetta 2 is an emulator that allows applications that were originally built for Intel-based Macs to run on Apple silicon Macs. Rosetta 2 translates the Intel instructions to Apple instructions in the background, without the user noticing. Rosetta 2 is automatically installed when an Intel app is launched for the first time on an Apple silicon Mac. Rosetta 2 can also translate Universal apps that contain both Intel and Apple instructions, if the user chooses to run the Intel version. Rosetta 2 is not a substitute for creating native apps for Apple silicon, but it is a temporary solution to ease the transition. References: Rosetta 2 - Apple Developer, How to Launch the Intel Version of a Universal Apple Silicon App