what does windows size value mean in TCP header

The window size value in the TCP header indicates the amount of data (in bytes) that the sender can transmit to the receiver before receiving an acknowledgment. Essentially, it specifies the size of the receive window, which is the amount of buffer space available to the receiver for incoming data. The window size value helps to regulate the flow of data between the sender and receiver, preventing congestion and ensuring efficient data transfer. A larger window size value indicates that the receiver has more buffer space available and can handle more data, while a smaller value indicates that the receiver is more limited in its capacity to receive data