A firewall is a piece of software which helps protect your computer from online attacks. Any computer you use to access the internet should have a firewall installed.

It's recommended that your firewall is set to monitor incoming and outgoing internet traffic. This means that you have control over the information that enters and leaves your system.

Which firewall?

Windows XP, Windows Vista, Windows 7 and Mac OS X operating systems have built-in firewalls. Look up your help menus for instructions on checking or setting up your firewall.

Alternatively, you can buy a firewall from a computer retailer.