A typical home network layout that allows connecting few computers and sharing an internet connection is shown in the following diagram.

Three computers connected through a router to the internet

The modem's role is to communicate with our Internet Service Provider (ISP) and be the gateway to the internet. The most common broadband internet connections today are DSL, Cable or T1. If you have a phone-line dialup connection. Usually modems have a single Ethernet port that allows connecting to it directly only one PC using a network cable. Instead, we will connect the modem to a device called router or wireless router. Note that these days you can find also modem-router or mode-wirelss-router unified boxs, but logically it is the same.

A router is a hub-like device that has few ports for the local network computers and a single port for connecting to an external network, in our case the internet. Typical routers have 4 local ports or sometimes even more, but sometimes less.

In case we want to connect computers to the network using wireless connection, we need a wireless router. Typical wireless routers have both wired network ports and are concurrently able to connect several computers (desktops, mobile laptops, etc) with wireless connection in addition to the wired connected devices.

Wireless routers are also capable of acting as a DHCP server and dynamically assign local IP addresses to the local computers as we discuss in the previous section (so manual IP assignment is not needed).

Since the physical medium used in wireless connection is public (the air around us), all the wireless connections should be secured and encrypted so none of our "friendly neighbors" will be able to use our connection or eavesdrop on the data transferred over the air. We will see how to configure a secured wireless connection.