What is the main function of a firewall?

The main function of a firewall is to block unauthorized access while allowing outward communication. Firewalls are essential security devices in network architecture that monitor incoming and outgoing traffic based on predefined security rules. They act as a barrier between a trusted internal network and untrusted external networks, such as the internet. By selectively filtering this traffic, a firewall prevents potential threats, such as hackers or malicious software, from entering the network, while still permitting users to access resources on the internet. This capability is crucial in maintaining network security and safeguarding sensitive information from unauthorized access, ensuring that the network remains both functional and secure.