The TCP retransmission means resending the packets over the network that have been either lost or damaged. Here, retransmission is a mechanism used by protocols such as TCP to provide reliable communication. Here, reliable communication means that the protocol guarantees the packet’s delivery even if the data packet has been lost or damaged. The networks are unreliable and do not guarantee the delay or the retransmission of the lost or damaged packets. The network, which uses a combination of acknowledgment and retransmission of damaged or lost packets, offers reliability. For more details please read TCP congestion control article.
