IP address

Wiki ▸ 🔰 Foundations ▸ IP address

In order for one machine to send a message to another, it must have the name of the place at which the intended recipient can be found. This name is called an address. At this fundamental level, computer addresses work exactly the same way as postal addresses. If you've ever sent a postcard to a family member or friend while on vacation, you've written an address. Likewise, if you've ever sent an email to a coworker, chatted with a friend on Facebook, or placed a telephone call, you've used an address to direct the message towards your recipient. Postcards use mailing addresses, Facebook chats use Facebook user names, e-mails use email addresses, and telephone calls use telephone numbers. These are all examples of addresses.

In many modern digital networks (like the Internet), the "place" in the network at which a given machine can be found is an address called an Internet Protocol (IP) address. Though plentiful, this notion of "place" is not infinite; it is possible to run out of IP addresses. In order for any two machines to be able to communicate with one another, both of them need to have their own IP address. When one sends a message to the other, it will write its own IP address on the message's envelope in the source IP field and, unsurprisingly, it will write the IP address of its intended recipient on the message's envelope in the destination IP field. These message envelopes are called packet headers.

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