| A bridge, as you may or may not know, is a boundary between populations of LAN stations for the purpose of relieving overcrowding/congestion. A transparent bridge is the most common bridge type. It was originally developed at DEC in the early and was incorporated into the IEEE 802.1 standard. To conform to this standard, a bridge must use both learning and the spanning tree. Many Ethernet/IEEE 802.3 networks use transparent bridges.
Its transparency owes to the fact that end stations are not aware of its presence and operation. Also, it does not have knowledge of the network's topology; it only knows which identifiers are known on each of its ports. They analyze the source address of incoming frames from attached networks, and uses its table for traffic forwarding. It has three tasks: learning, forwarding, and filtering. | 
