A firewall is a network device that performs stateful packet inspection, which means it analyzes incoming and outgoing network traffic based on predefined rules and filters, and allows or blocks packets based on their source, destination, protocol, port, or content. A firewall can enhance security by preventing unauthorized access, blocking malicious traffic, enforcing policies, and logging events. A firewall can be hardware-based or software-based, or a combination of both. Reference: https://www.comptia.org/training/books/a-core-1-220-
1101-study-guide (page 78)