A Magic Packet is a special network message used to wake up a computer from a low-power state, such as sleep or hibernation. It is part of the Wake-on-LAN (WoL) technology, which allows remote management of devices over a network. The packet contains a specific sequence of bytes that the target computer recognizes, prompting it to power on. To send a Magic Packet, a device must know the Media Access Control (MAC) address of the target computer. When the packet is received, the network interface card (NIC) of the computer listens for it, even when the computer is turned off, allowing for convenient remote access and management.