When you connect to another computer somewhere it's to ask it to provide some service to you. Those computers are called servers because they have what you want and are configured to provide it. There are servers that provide email, others that provide web pages, some let you store or download files. Most computers don't offer any services at all.

To access a another computer (a server), you'll need a way to connect your computer to a network. A network is just a bunch of computers connected together. In most cases you'll have to connect to a network using an Internet Service Provider (ISP). The ISP will make all the connections for you and tell you what you have to do to connect when you subscribe to the service.

Most ISPs have lots of connections so they use various techniques to manage all the connected computers. Since each computer on their network will be doing something different from all the others, there has to be some way ensure that the computer interactions are kept separate. If one computer tries to go a web site how is that web site going to know where to send the web page? To manage this, the ISP assigns every computer a unique address and this address tells a server who is asking for what and where to send the stuff that was requested. This unique address is called an Internet Protocol (IP) address.

Thing is, an ISP can't afford to give you a permanent address so it assigns a special temporary address. Temporary in this case may last months, but it will eventually change. The temporary IP address is assigned by a server using Dynamic Host Control Protocol (DHCP) which sets up everything your computer needs to know for it to connect to the network (usually the Internet). Because of this, you can't count on your IP address staying the same. If you wanted to set up a server on your computer it wouldn't work because its address will change so no one could find it.

Every time you connect to another computer, it will record your network configuration at the time of that connection. Even though you won't know what address the ISP has assigned to your computer, any server you connect to will. The server has to know your real IP address in order to send web pages or email to your computer so to find out your real IP address, you have to ask a server.

If you wanted to have your web pages on the Internet without paying a web host (companies that charge for a permanent address), you would have to install and configure a web server on your computer (good choices are Apache (get the httpd server) and Xitami). A web server is a special program that will display your web pages on your own computer. Even though you don't have a permanent IP address you can tell people how to connect to your web server if you know your current IP address. Send an email telling them to just type in your IP address.

An ISP isn't going to let you run a web server though. The normal access to a normal web server uses reserved access points (ports) so you have to configure your web server to use a different, non-restricted port (8080 usually). It's not difficult, just read the documentation. But knowing how to run a server by knowing your real IP address is kind of handy.

Running a server on your computer is pretty cool if you like to experiment. Download a web server (the Apache httpd server is the best and most common). Download and install some scripting languages like PHP or perl so you can get fancy if you want. Once the server is installed, you can test out your web pages and scripts on your computer without having to connect to any other server. It runs locally (your computer) so you can see how things work right away. To see your web pages locally, just type, localhost, in your browser's address bar. If you know your IP address you can enter that as well.