Apple fundamentally changed what it means to be on a network when it introduced its AirPort devices in the summer of 1999.
An AirPort network consists of an AirPort Base Station, an AirPort card for each Mac you want to connect, and an account with an ISP. The AirPort Base Station has a built-in modem for dial-up Internet connections, but you may also connect the base station to a broadband cable or DSL modem using an Ethernet cable for faster connections.
Your AirPort cards do not talk directly to the Internet but rather to the base station—otherwise known as an access point. The base station manages the connection to the Internet through your ISP.
Until a few years ...