Computers need networking hardware in order to connect to each other.
Network Interface Card (NIC)
Any computer that is to be connected to a network, needs to have a network interface card (NIC). Most modern computers have these devices built into the motherboard, but in some computers you have to add an extra expansion card (small circuit board).
To connect together different devices to make up a network, you need cables. Cables are still used in most networks, rather than using only wireless, because they can carry much more data per second, and are more secure.
A router can form a LAN by connecting devices within a building. It also makes it possible to connect different networks together. Homes and businesses use a router to connect to the internet. A router can often incorporate a modem within the hardware.
Modem
A modem enables a computer to connect to the internet over a telephone line. A modem converts digital signals from a computer to analogue signals that are then sent down the telephone line. A modem on the other end converts the analogue signal back to a digital signal which another computer can understand.
Hubs, bridges and switches allow multiple devices to connect to the router and they transfer data to all devices on a network. A router is a more complex device that usually includes the capability of hubs, bridges and switches.
Hub
A hub broadcasts data to all devices on a network. This can use a lot of bandwidth as it results in unnecessary data being sent - not all computers might need to receive the data. A hub would be useful to link up a few games consoles for a local multiplayer game using a wired LAN.
Bridge
A bridge is used to connect two separate LAN networks. A computer can act as a bridge through the operating system. A bridge looks for the receiving device before it sends the message. This means that it will not send a message if the receiving computer is not there. It will check to see if the receiver has already had the message. This can help save unnecessary data transfers, which improves the performance of a network.
Firewall
A firewall is a device, or a piece of software that is placed between your computer and the rest of the network. If you wish to protect your whole LAN from hackers out on the Internet, you would place a firewall between the LAN and the Internet connection. A firewall blocks unauthorised connections being made to your computer or LAN. Normal data is allowed through the firewall (e.g. e-mails or web pages) but all other data is blocked.
