payload，翻译过来是有效载荷
通常在传输数据时，为了使数据传输更可靠，要把原始数据分批传输，并且在每一批数据的头和尾都加上一定的辅助信息，比如数据量的大小、校验位等，这样就相当于给已经分批的原始数据加一些外套，这些外套起标示作用，使得原始数据不易丢失，一批数据加上“外套”就形成了传输通道的基本传输单元，叫做数据帧或数据包，而其中的原始数据就是payload
The essential data that is being carried within a packet or other transmission unit. The payload does not include the "overhead" data required to get the packet to its destination. Note that what constitutes the payload may depend on the point-of-view. To a communications layer that needs some of the overhead data to do its job, the payload is sometimes considered to include the part of the overhead data that this layer handles. However, in more general usage, the payload is the bits that get delivered to the end user at the destination.
转自：https://www.zhihu.com/question/26689845/answer/126341952
根据上面的描述，讲师提到的payload，就是指安全测试数据