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What is a firewall?

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Quick answer

A firewall is a security system that monitors and controls what data is allowed in and out of a network or device. Acting like a guard at a gate, it blocks suspicious or unauthorized traffic while letting safe traffic through.

Key things to understand

  1. It controls incoming and outgoing network traffic.
  2. It blocks unauthorized or suspicious connections.
  3. It can be hardware, software, or both.
  4. It's a first line of defense in cybersecurity.

People also ask

What does a firewall do?
It monitors network traffic and blocks unauthorized or dangerous connections while allowing safe ones.
What's the difference between hardware and software firewalls?
Hardware firewalls protect whole networks at the gateway; software firewalls run on individual devices.
Do I need a firewall?
Yes — firewalls are a basic, essential layer of protection against online threats.