A network scanner is a tool used to discover devices and services on a computer network. It works by sending requests to various IP addresses within a specified range and analyzing the responses. This helps network administrators identify active devices, open ports, and potential vulnerabilities. Network scanners can be used for various purposes, including security assessments and network management. Popular examples of network scanners include Nmap and Angry IP Scanner. By providing insights into the network's structure, these tools help ensure that systems are secure and functioning properly.