Internet Addresses

Packets of Information

TCP/IP Protocols | Packets of Information | Addresses | The Naming System | Finding Addresses | Going Futher

How does information get transferred between computers on the Internet? A pretty good analogy is that of letters and the usual mail system (the one that computer types call "snail mail", because it is so slow compared with electronic mail!). The information is transferred in what are called electronic packets, which are something like letters containing information. If the packets are like letters, they must have an address. Just as normal letters must have an address on the front to make delivery likely, TCP/IP communication depends on addresses being included in each packet. Not surprisingly, these addresses are commonly termed "IP addresses". So, if someone asks what your IP address is, she is asking the electronic equivalent of what your post office address is.

As these packets of information move through the network, electronic devices called routers use these IP addresses to decide whether to keep a packet in a local network or to forward it to a different network. This is a complex task, because there are many networks that either comprise the Internet, or that are attached to it through some gateway.

Thus, routers and gateways in the network serve much the same function that different levels of post offices serve in the usual mail system, with each level of the postal system deciding whether the letter in question should be delivered locally, or forwarded to another part of the postal system.