What Is a Firewall?

Written by Coursera Staff • Updated on

Learn about the role firewalls play in safeguarding networks and devices from cyber threats.

[Featured Image] Cybersecurity analyst working on creating a firewall to secure the network.

A firewall is a network security device. It creates a barrier between a trusted network and an untrustworthy network. For example, a firewall can restrict internet traffic from accessing your private network. It acts like a gatekeeper, controlling incoming and outgoing traffic according to a predetermined set of security rules. 

Firewall vs. antivirus: What's the difference?

Antivirus is security software. A firewall can be hardware, software, or a combination of the two. Firewalls focus on preventing unauthorized access and monitoring network traffic. The primary goal of antivirus software is to prevent, monitor, and eliminate harmful code or software.


Types of firewalls

The list below outlines a few examples of firewall types: 

  • Hardware firewall: Also known as an appliance firewall, this type of firewall is a separate, self-contained piece of hardware designed to filter network traffic. Hardware firewalls are popular among larger organizations with many computers in their network.

  • Software firewall: Software firewalls are installed onto a host device to prevent malicious traffic. To provide protection to several computers, a version of the software must be installed on each one. For this reason, software firewalls are popular among individuals and small businesses.

  • Application firewall: This type of firewall is designed to control outgoing and incoming traffic and provide protection at the application layer. Examples include web application firewalls (WAF), which protect web servers and sites, and database firewalls (DB).

  • Network firewall: Network-based firewalls monitor incoming and outgoing traffic from the internet to secure local area networks (LANs). They prevent security issues like malware threats from impacting the entire network by blocking unauthorized access to all connected devices.

Read more: Cybersecurity Terms: A to Z Glossary

Related terms

Learn more about firewalls with Coursera

If you’re ready to get started in a cybersecurity career, consider enrolling in the Google Cybersecurity Professional Certificate on Coursera. Learn how to use job essential tools like Splunk, Chronicle, playbook, and more. This program is designed ​​to help individuals with no previous experience find their first job in the cybersecurity field, all at their own pace. 

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