If the sending computer doesn't receive notification from the receiving computer within an expected time frame, the segment is retransmitted. TCP also maintains a flow-control window to restrict transmissions. The receiver advertises a window size, indicating how many bytes it can handle. Re-sequences segments if they arrive out of order. Tosses packets if data became corrupt during transmission.
Discards duplicate segments.
Maintains flow control to manage a connection's transmission rate. Network applications and user expectations changed with the growth of the Internet. It interprets dropped packets as a sign of congestion. The goal of TCP is for individual connections to burst on demand to use all available bandwidth, while at the same time reacting conservatively to inferred problems in order to alleviate congestion. It allows the sender to transmit multiple packets before it stops and waits for an acknowledgment.