What do you call the feature in packet-based data transmission protocols (Like TCP) that governs the amount of data (number of packets) the receiver is able to accept from the sender?

What do you call the feature in packet-based data transmission protocols (Like TCP) that governs the amount of data (number of packets) the receiver is able to accept from the sender?

• Sequence Number
• Jitter
• CiDR
• Sliding Window 

EXPLANATION

The sliding window feature informs the sender how much data (packets) the receiver can accept.  Since networks are dynamic and are prone to congestion this number fluctuates depending on a number of variables.  Essentially if my PC is sending a file to the server it may send 10 packets out of 20,000 to start the transfer.  If the server was able to receive all of those packets it may request more.
 This will continue until the server either can't accept more because its buffer is full or some packets were missed because of congestion.  The sender will then retransmit missed packets and begin to scale down the window until the server and the receiver are in sync.  This back and forth continues to the end of the transfer.
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