Introduction
If you want to connect a single computer or a network to the Internet then you need to use some specialised equipment. There are a number of choices, including a modem, a broadband modem, a broadband router and a wireless broadband router (although there are other pieces of equipment you can use).

Bandwidth
Before we look at different pieces of equipment to connect to the Internet, there is one important word to take note of here: 'bandwidth'.

Bandwidth refers to the volume of data that can be sent or received in one second. The higher the bandwidth, the more data you can send in any second. This is very important because some devices can handle a higher bandwidth than others. If you are using a broadband modem (see below), for example, that has a higher bandwidth compared to a dial-up modem (see below) and you won't be waiting too long for a film to download, perhaps a few minutes at most. A dial-up modem, on the other hand, uses a low bandwidth and a film might take many hours to download.

Bandwidth can be given as a frequency (e.g. 4 KHz) which tells you the range of frequencies that can be used. It can also be given as a transmission rate, in bits per second (e.g. 56 kbps)

Modem (also called a 'dial-up modem')
This is a piece of equipment used for sending and receiving data from one computer to another computer using the existing phone network.

A modem works by taking the packets of data (which are digital signals) from a computer and converting them into analogue signals, which the phone network uses. The analogue signals then pass along the phone network from computer to computer, from network to network, until the final destination is reached. At the destination, another modem converts back the analogue signals into the original digital ones and then passes these to the destination computer.

Advantages and disadvantages of modems
In this way, the existing, widespread phone network, which only uses analogue signals, can be used by computers, which are digital devices. On the other hand, modems cannot send large volumes of data at once. They are therefore of little use when streaming files, and the time taken to download files such as music or films may make them frustrating. In addition, the phone line, just like making a phone call, is engaged whilst the modem is in use. This is why it is also known as a 'dial-up' modem; you have to dial up the phone number provided by your Internet Service Provider (ISP) to make a connection to the Internet and all the time you are on the phone using the Internet, your phone cannot be used for other things, such as making and receiving phone calls or sending faxes.

Broadband modem
For many years, most homes used dial-up modems but as we have seen, these are slow and you cannot use your phone line for making or receiving phone calls whilst you are connected to the Internet. As technology advanced, many homes and businesses now make use of broadband modems. These pieces of equipment work in much the same way as dial-up modems, connecting to your phone line, converting digital signals into analogue signals and back again. However, they make use of a much wider range of frequencies than dial-up modems. Some of those frequencies can be used for the Internet but crucially, the frequencies that we use for speaking can be reserved for speaking. This means that we can now use both the Internet and make and receive phone calls at the same time.

One thing to note about broadband modems - they are designed to allow you to connect only one computer to your broadband connection. For many homes and businesses these days, that is a problem, as they have many devices that need to access the Internet!

Broadband router
Another piece of equipment in wide use is a 'broadband router'. This piece of equipment combines a broadband modem with a switch, so that you can connect not one computer but many computers or a whole network to your broadband connection. The router usually has an 'Admin' area. You can log in to this area using a login and password and set up the router and any security features, such as a 'firewall'. This is a piece of software that stops unauthorised users getting access to the network.

Wireless broadband router
If it weren't enough to have broadband routers, it is very common to find 'wireless broadband routers' in homes and businesses today. These work in the same way as a broadband router but you can connect devices wirelessly to the router as well as physically, using cables. That means that those wireless devices can also use the broadband connection to access the Internet.

Using wireless broadband router software, you can login using the administrator's login and password and set up the firewall. You can also set up the wireless security features that are commonly found. There are two features you are likely to find:

1. A password. You set up a password for wireless users. That means that anyone with a wireless device has to enter the correct password into their device before they can get access to the Internet connection.
2. MAC addresses. Allowable MAC addresses are entered into a table. Every device that can connect to the Internet has a MAC (Media Access Control) address. If you put the addresses of only the devices you want to allow to make a connection, then any device with a MAC address not in this table will not be allowed access to the Internet connection.

It is always a good idea to prevent unauthorised users from getting access to your network. One reason is they might be up to no good. The second reason is they might be downloading large files, which could slow your own use of the Internet down or even cost you money if you are paying for how much data is downloaded.

Q1. What is meant by ‘bandwidth’?
Q2. Explain why the bandwidth of a connection is important.
Q3. Bandwidth can be expressed using one of two units. What are they?
Q4. Explain how a modem works.
Q5. What is the difference between a broadband modem and a broadband router?
Q6. Describe two security features commonly found in wireless broadband routers.