A firewall acts as a digital gatekeeper within computer networks, diligently analysing incoming and outgoing data packets based on predefined security rules. Its primary mission is to erect a protective barrier between the internal network and external sources, such as the vast expanse of the internet. In this role, it sifts through data traffic, effectively separating legitimate content from potential threats like viruses and malicious hackers. By enforcing these security rules, firewalls play a crucial role in preserving the integrity and security of the network. They permit the passage of legitimate data while decisively blocking or flagging any signs of suspicious or malevolent activities. In doing so, they substantially reduce the network's vulnerability to cyber threats and unauthorized access, serving as a vital component of modern digital security strategies.