A broadcast address is a special type of network address used to send data to all devices within a specific subnet. When a message is sent to a broadcast address, every device on that subnet receives the message, allowing for efficient communication without needing to address each device individually. In IPv4 networks, the broadcast address is typically the highest address in a subnet. For example, in the subnet 192.168.1.0/24, the broadcast address would be 192.168.1.255. This feature is useful for tasks like network discovery and sending updates to all devices simultaneously.