A host address is a unique identifier assigned to a device on a network, allowing it to communicate with other devices. In the context of the Internet, host addresses are often represented as IP addresses, which can be either IPv4 or IPv6. Each address helps route data to the correct destination, ensuring that information reaches the intended device. Host addresses are essential for network functionality, as they distinguish one device from another. Without unique host addresses, data packets would not know where to go, leading to confusion and communication failures. Proper management of host addresses is crucial for maintaining efficient network operations.