A Firewall is a fundamental component in the field of Computer Networks and plays a critical role in protecting computer networks from cyber threats and unauthorized access. It acts as a security system that monitors incoming and outgoing network traffic and enforces predefined security rules to allow or block data packets. The concept of firewalls emerged with the rapid growth of the internet and the increasing number of cyberattacks, such as intrusions and denial-of-service attacks. Firewalls are considered a core element of Cybersecurity, as they help ensure data confidentiality, integrity, and availability. Firewalls can be classified into several types based on their functionality: Packet Filtering Firewalls Stateful Inspection Firewalls Application Layer Firewalls These systems operate by implementing security policies that control traffic based on parameters such as IP addresses, ports, and protocols. Additionally, firewalls can be integrated with other security technologies, such as intrusion detection systems, to enhance overall protection. Despite their importance, firewalls alone cannot provide complete security. They must be used alongside other security measures, such as encryption and antivirus software, to achieve comprehensive protection. Therefore, proper configuration and management are essential to ensure their effectiveness in modern network environments. Ms. Fatimah Haider Jasim University of Al-Mustaqbal – The First and Leading Private University