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How does broadband work?

An ethernet cable plugged into a globe

Broadband is the name given to any fast, permanent internet connection. It can be delivered by cable, satellite, mobile, fibre optics and ADSL (the most popular way).

Andrew Stucken | 9th September 2010

When the internet revolution began, users accessed the net via dial-up and a ‘modem’ - a piece of hardware that converts signals from your computer so they can travel down a telephone line, and vice-versa. (A modem is a bit like an interpreter who translates back and forth between two languages.)

As anyone who used to go online this way will know, it could be painfully slow – and it tied up your phone line.

The difference between dial-up and broadband is like the difference between a country lane and a motorway. Replace a single band with separate bands for uploading, downloading and voice - and you speed up traffic many times over. Instead of one, narrow band you get a broader band – hence ‘broadband’.


You need certain hardware to use ADSL broadband - a modem or router, and microfilters to remove the hiss of broadband from your telephone line. A router looks a bit like a modem but is really a self-contained little computer. It connects your network to the network used by your ISP (internet service provider).

ADSL comes from your local BT phone exchange via the old copper wires. Your ISP will test and activate the line for you.

Your modem or router plugs into your phone socket, along with a microfilter (a small plastic box). Your computer needs to connect to the modem/router as well, either with wires or wirelessly.

ISPs usually supply a CD-Rom with software for setting up your connection.


Some Cable TV companies offer a cable internet connection via their existing wiring - as well as carrying their TV programmes, an internet connection is included as well. The speeds are comparable to ADSL, though cable is nowhere near as widely available.


Satellite broadband is still in its infancy and is set up using a satellite dish (as you would for satellite TV). Both a one-way (download only) and a two-way satellite internet connection are available. For very isolated rural areas, satellite can be the only broadband option - but adverse weather conditions can interrupt the service.


Mobile is the newest form of broadband. A small USB device called a ‘dongle’ or a data card - or just hooking your computer up to a compatible mobile phone - enables you to access the internet wherever there is a mobile phone signal.

You may also have heard the term ‘Wi-Fi’. This isn't an internet connection itself - it connects to your own connection and then broadcasts it over a wide area without wires. A wi-fi mini-network at your home means you can access the internet anywhere - even in your garden. Better still, several users can connect at once.


ADSL might seem lightning fast compared to old dial-up connections, but it has its limitations. As a result, the telephone and cable companies are hard at work installing the next generation of internet service - fibre-optics.

Fibre-optics are tiny wires that transmit pulses of light. Since light is the fastest thing in the universe, they're much faster than electric ADSL cables. This means you can get internet speeds up to five times faster than the fastest ADSL connections.

The companies have to replace all the wires in the ground across the country, so fibre-optics aren't available in a lot of places yet. Eventually though, everyone in the country should be able to enjoy these high speeds!

Andrew Stucken

Andrew Stucken

Andrew cut his journalistic teeth with the local press, and has since moved on to writing for major national websites specialising in technology and money-saving. He has also written for The Times and other national newspapers.