Your Place on the Internet

If you use the Internet, somewhere along the way you signed up for an Internet account. Although you think of that account as allowing you to connect to the Internet, what it really allows you to do is connect to someone else's network for a fee. This network, in turn, is connected to the larger global Internet. An Internet Service Provider (ISP) is a company that sells access to the Internet. They do so by creating a network to which their customers can connect. These connections may happen through a dialup modem, a cable TV system, or high-speed DSL links through your phone line. My own connection is a two-way wireless system in which an antenna on my roof connects to an antenna on a mountaintop almost forty miles south of me.

However the connection happens, you connect to your ISP's network. Once you're part of your ISP's network, you reach the rest of the Internet through your ISP's router or routers. Schematically, it looks something like Figure 3.2.

Figure 3.2: Your Computer on the ISP Network.

Even though you're not in the same building with all the rest of your ISP's customers, you're still very much a part of a 'local' area network. The connection is by way of modem (dial-up, cable, or DSL) but at your ISP's central location your connection is networked with the connections of other customers through a hub or switch, as I described in Chapter 1. The ISP's router then acts as your gateway to the Internet.