A Next-Generation Firewall (NGFW) is a part of the third generation of firewall technology, combining a traditional firewall with other network device filtering functionalities, such as an application firewall using in-line deep packet inspection (DPI), an intrusion prevention system (IPS).
Firewalls are security perimeter devices that monitor all traffic entering and exiting the network. Based on security rules assigned to the firewall, these devices determine if traffic is safe, allowing it to pass through, or dangerous, and must be blocked. A firewall acts like a physical barrier or wall preventing malicious network packets, such as malware and external cyber-hacking attempts, from breaching internal networks.
Intrusion detection systems, routers, proxy servers, VPNs and antivirus solutions do not constitute firewalls, but firewall architectures are often incorporated into other security solutions.