Final answer:
An application-level firewall, often called a proxy server, filters traffic based on applications, acting as an intermediary between users and services, providing granular control over network traffic.
Step-by-step explanation:
The type of firewall that is also known as a proxy server is application-level firewall. An application-level firewall, which is sometimes referred to as a proxy-based firewall, filters traffic based on applications or services. Essentially, it acts as an intermediary (the proxy) between end-users and the services they wish to access. By doing so, the firewall can analyze and potentially block incoming and outgoing traffic based on the content of the messages, rather than just the IP addresses and port numbers. This type of firewall operates at the highest layer of the OSI model, which is the application layer, and allows for more granular control over the network traffic.