Final answer:
A unicast address is used to send data to a specific, unique device on a network, ensuring that the transmission reaches the correct destination interface.
Step-by-step explanation:
A unicast address represents any one interface from a group of interfaces, any one of which can accept a transmission. When we send data to a unicast address, we are addressing a specific device on the network. Unicast is the most common form of communication on IP networks, including the Internet. Each device that is capable of connecting to the Internet has a unique IP address which is its unicast address. This address ensures that the data sent across the network reaches the correct destination interface.