Data networks are systems that connect computers and devices to share information and resources. They allow users to communicate, access the internet, and transfer files. Common types of data networks include local area networks (LANs), which connect devices in a small area, and wide area networks (WANs), which cover larger geographical distances. These networks use various technologies, such as routers and switches, to manage data traffic and ensure efficient communication. Security measures, like firewalls and encryption, help protect the data being transmitted. Overall, data networks are essential for modern communication and information sharing.