ARP stands for Address Resolution Protocol, an internet networking term. It is a method for finding a host's Ethernet address, also known as media access control, or MAC address, using its Internet Protocol, or IP, address.
A sender trying to find a host’s Ethernet address broadcasts an Address Resolution Protocol packet containing the Internet address of another host and waits for that host to send back its Ethernet address.
Every website host maintains a cache of address translations to reduce connection delays and loading time. Address Resolution Protocol allows Internet addresses to be independent of their Ethernet addresses, but it only works if all internet hosts support the protocol.