Which term describes a device that protects networks from outside threats?

A device designed to protect networks from outside threats is referred to as a firewall. Firewalls serve as a barrier between a trusted internal network and untrusted external networks, such as the internet. They monitor and filter incoming and outgoing network traffic based on predetermined security rules, effectively preventing unauthorized access and potential attacks.

While routers, switches, and access points are vital components of network infrastructure, they serve different purposes. Routers direct traffic between different networks, switches connect devices within a local network to facilitate communication, and access points allow wireless devices to connect to a wired network. None of these components inherently provide the protective functions that firewalls are specifically designed to offer, which is crucial for maintaining network security.