IP addresses, and using the Internet, can be (mis)understood by likening the process to visiting a restaurant. The following text compares a restaurant visit (plain text) to an Internet session (bold text).
Dynamic IP Address:
When you enter a restaurant, you're seated at a table. Restaurant workers
typically refer to tables by a number. The table's number now identifies you for the
remainder of your stay at the restaurant.
When you log on to your Internet service provider (ISP), you're given an
identifying number, an IP address. This number is associated with you until you log
off.
A waiter or waitress takes your order to the kitchen, and returns with the food
you've ordered, using the table number as a guide. "Steak for table five, table three
ordered onion rings…" If you had moved to a different table there would be momentary
confusion, and you might receive a lapful of hot coffee (accidentally, of course).
Using a Web browser, e-mail program, or other software, you request
information from the Internet. The TCP/IP protocol (waiter) exchanges data
between your computer and the Internet (kitchen). Numerous packets of data (to
put it mildly) course through the Internet. Using the IP address, the packets can be
properly routed to the computers that requested them.
You finish your meal and leave. The table is now free for another patron to use.
You log off. The IP address you had been using is now free to be reassigned
to another user.
Static IP Address:
You are Frank Famousguy, movie star, sports hero, pop sensation, and
neurosurgeon. You frequent the restaurant almost daily, and are good friends with the
owner. The restaurant owner reserves table three (the best in the house with a nice view
of the lake, trees, and neighboring nudist colony) for your personal use. Anytime you
come in, table three will be there waiting for you. Your friends (and possibly the general
public) know that this is your personal table, and that if you're in the restaurant they can
find you there.
You've paid money to your ISP for a static IP address, or it was included
with your broadband connection. Anytime you log on to your ISP, this is the
address you will receive. Static IP addresses are useful if your computer will be
acting as a server of some type (web sites, e-mail, games, etc.) A static IP address is
necessary in these cases, as computers worldwide will need to know your computer's
address in order to access the content being served.