Address Resolution Protocol (ARP) is a network protocol used in the communication between devices on a local network. It translates or maps a device's IP address, which is used at the network layer (Layer 3) of the OSI model, to its corresponding physical or MAC address, which is used at the data link layer (Layer 2).
When a device needs to communicate with another device on the same local network, it uses ARP to determine the MAC address associated with the recipient's IP address. The process generally involves sending a broadcast ARP request packet asking, "Who has this IP address?" The device with that IP address responds with an ARP reply, providing its MAC address. This information is then stored in an ARP table, allowing for efficient communication without needing to perform ARP requests repeatedly for the same device.
In summary, ARP is crucial for enabling devices on a local network to find each other and communicate effectively by linking IP addresses to their corresponding MAC addresses.