A protocol, or set of rules, for transmitting data over a network. IP does not describe how a network is physically set up, but instead how data are to be encoded to be transmitted over an existing physical network. IP handles packets from a source host to a destination host. It facilitates communicating between computers ("nodes") on interconnected networks, even when they are not on the same local network as each other, by routing data through the connections (or "gateways") between networks. This makes internetworking, including the global Internet, possible.
There are two versions of the Internet Protocol in use: IPv4 and IPv6. Most of the Internet still uses IPv4. Computers can be configured to use both, even on the same network interface, though most residential ISP's don't assign IPv6 addresses.
An IP address is a computer or other device's address on the network. An IPv4 address, often called just an "IP address," consists of 4 octets separated by dots. Each octet ranges from 0 to 254. An IPv6 address consists 64 hexadecimal digits, separated by colons into 8 groups of 8.
This tag is appropriate for questions about obtaining, assigning, or querying information about IP addresses and configuration in Ubuntu, or any other Ubuntu-related questions about the Internet Protocol. For Internet questions that are not about IP or IP addresses, use internet. For non-IP-related networking questions, use networking.