What does 'sliding window' in TCP refer to?

The term 'sliding window' in TCP refers to a flow control mechanism that enables efficient data transmission between sender and receiver. It works by allowing the sender to transmit multiple packets before needing an acknowledgment for the first one, thus improving network utilization and throughput.

The sliding window adjusts dynamically based on network conditions, controlling how many packets can be sent without receiving an acknowledgment. This prevents the sender from overwhelming the receiver and helps manage varying network speeds, ensuring that data flow is adjusted based on the current state of the connection. By using this mechanism, TCP can make better use of available bandwidth and minimize delays, accommodating different levels of congestion and packet loss that may occur on the network.

Each window size can change, which means that the sender can increase or decrease the amount of data sent based on feedback from the receiver about their ability to process the data. This adaptability is crucial for maintaining efficient communication and is a fundamental aspect of TCP's reliability and performance features.