Which one among the following is the primary purpose of firewall ?

A firewall is a fundamental network security device designed to monitor and filter incoming and outgoing network traffic based on an organization's previously established security policies. Its primary purpose is to prevent unauthorized access to or from a private network by acting as a barrier between a trusted internal network and untrusted external networks, such as the internet.

• Option A: Backup data is managed by storage systems or cloud services, not firewalls.
• Option B: File encryption is handled by cryptographic software or protocols like SSL/TLS.
• Option D: Firewalls do not increase computer speed; in fact, they may slightly increase latency due to the time taken for packet inspection.

Firewalls can be hardware-based, software-based, or both, and are essential for protecting against cyber threats, malware, and unauthorized intrusions.