Learn in the textbookIP Addresses and the Address System
DefinitionAn IP address (IPアドレス) is the number that identifies the device you are communicating with on a network, and it is not the same thing as the MAC address (MACアドレス) built into a communication component.
ExplanationData travels in small units called packets, and a router (ルータ), the device that relays between networks, reads the destination IP address to choose the next hop. The address splits into a network portion (ネットワークアドレス部) that names the network and a host portion (ホストアドレス部) that names a device on it, with a value called the subnet mask (サブネットマスク) setting the boundary. Strings of digits are hard to remember, so people normally use a text domain name (ドメイン名), and a system called DNS looks up the matching IP address.
AnalogyThink of the delivery address on a parcel label. The street narrows it to a delivery area, and the house number picks out the home.
Memory hookIP stands for Internet Protocol, so the P means a set of communication rules, not a number.