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firewall

FY-er-wawl /ˈfaɪərˌwɔːl/

nounB2TOEFLIELTS

technicalgeneral

A network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules.

A firewall acts as a barrier between a trusted internal network and untrusted external networks (like the internet), filtering traffic to prevent unauthorized access and malicious activity.

The story behind the word. The word 'firewall' started its life in the physical world, referring to a wall constructed to prevent the spread of fire from one part of a building to another. It's a barrier designed to contain danger. In the digital realm, this powerful image was adopted in the late 1980s to describe a system that acts as a protective barrier, preventing the 'fire' of malicious internet traffic from spreading into a private network. A perfect metaphor for digital defense!

Word relationships

security barrier: A more general term for any protective obstacle.
packet filter: Describes a specific function of a firewall.

open network: A network with no security restrictions.
unprotected network: A network lacking security measures.

Commonly confused with

antivirus software: A firewall protects against unauthorized network access; antivirus software protects against malware once it's on your system.

Collocations

network firewall
software firewall
hardware firewall
configure a firewall
bypass a firewall

Idioms & expressions

put up a firewall (figurative)

Example sentences

"Make sure your computer's firewall is enabled to protect against unwanted intrusions." Explaining home network security.
"The corporate network is protected by a robust firewall system that blocks suspicious traffic." A company's IT infrastructure.
"Sometimes, a strict firewall can prevent online games from connecting properly, requiring adjustments." A discussion about online gaming.

Memory hook

Think of a 'FIREWALL' as a physical wall that stops 'FIRE' (bad data) from entering your network. Digital Fire Barrier

When not to use

Do not use 'firewall' to refer to general security software like antivirus programs. A firewall's primary function is network traffic filtering, not malware detection.

Fun facts

The first commercial firewall product was released in 1992 by Digital Equipment Corporation (DEC).
Many modern operating systems include a built-in software firewall.