A firewall is a barrier between your computer and others on the internet. Its purpose is to block attempts by malicious people to gain access to or destroy the information on your computer.
If you have broadband, it's especially important to have a firewall because your computer is permanently online, giving people (or their destructive or prying computer programs) plenty of time to try to attack it.
A firewall can consist of software – that is, a computer program – or hardware. A software firewall is the most important one to have. However, if your computer's operating system is Windows 10 it will already have the built-in Windows firewall called Windows Defender (see Microsoft's instructions of how to turn on Windows Defender). And these days, most broadband routers incorporate a hardware firewall.
There is lots more advice on internet safety on the Get Safe Online website.
Last updated 08/05/2019