Why is a firewall used in a computer?

A Firewall can be implemented as hardware, software, or a combination of both. It functions as a security guard for your computer or local network.

How it achieves Security: It analyzes data packets entering or leaving the network based on a pre-configured set of security rules. If a packet matches a rule that permits it, it is allowed to pass. If it contains suspicious signatures or originates from an untrusted source, the firewall blocks it.

Key Protections: By establishing this perimeter defense, a firewall protects systems from unauthorized remote access, blocks malware from communicating back to its hackers, and prevents automated network probes from finding vulnerabilities in your operating system.