Question & answer

What is a firewall and do you need one?

The short answer

A firewall controls which network traffic may reach your computer and which programs may phone out. You already have two. One sits in your router and one in Windows or macOS. Suite firewalls add easier controls and alerts on top. For most people the built-in firewalls are enough, as long as they stay on.

In detail

Think of a firewall as the doorman for network traffic. Inbound, it blocks connection attempts from the internet to your machine. Outbound, it can stop a suspicious program from sending data home. Your router does the first job for the whole house. That simply follows from how home networks work. Windows Firewall and the macOS firewall protect the device itself. Both are on by default.

Suites advertise firewalls because they give you more control and clarity. The firewalls in Bitdefender, Norton and ESET make per-app rules easy to understand. They warn you when a new program wants network access. They also adjust by themselves between home and public Wi-Fi. That is real value if you want to see what your machine talks to. G Data and ESET cater especially to those users.

The practical advice is simple. Keep the built-in firewall on. Let a suite replace it only if you will actually use the extra control. Also know what a firewall cannot do. It manages connections, not content. A phishing site you visit yourself walks straight past the doorman.