Address Resolution Protocol is a method computers use to find the hardware address of another device on the same local network. It takes a known IP address and asks, who has this address, then matches it to a MAC address so data can be delivered to the right network card. It keeps a short memory of these matches in an ARP table to speed up traffic. For example, when your PC wants to send a file to a nearby printer, ARP helps it learn the printer’s MAC address first.