In the early days of the Internet, when operating costs were really high and it was really important not to lose any data, then the system was set up for interactions to activate the flow of data.
在互联网的早期, 发送和接收数据的成本非常高, 所以任何形式的数据丢失都是不可以接受的, 所以网络系统被设计利用相互之间的交互 来决定何时发送数据.