A hub repeats information received from one host to all the other hosts. To understand this, consider HostA in Figure 1-2 sending a unicast message to HostB. When the hub receives this message; it will relay the message to both HostB and HostC. Even though the message was a unicast intended only for HostB, HostC also receives it. It is up to HostC to read the message and discard it after seeing that the message was not intended for it.