The document describes Packet Tracer files, which contain the configuration, topology, and settings of virtual network simulations created using Cisco Packet Tracer software. It explains that Packet Tracer files allow users to design, test, and share network layouts without physical equipment. The document also provides steps for creating and opening Packet Tracer files, including choosing "New" from the file menu to start a new simulation and adding devices by dragging them onto the topology pane. It recommends using Packet Tracer files to map and analyze the network of a university campus, identifying security controls and potential vulnerabilities to propose mitigation strategies.