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.
Payload in computing (sometimes referred to as the actual or body data) is the cargo of a data transmission. It is the part of the transmitted data which is the fundamental purpose of the transmission, to the exclusion of information sent with it (such as headers or metadata, sometimes referred to as overhead data) solely to facilitate delivery.
In the analysis of malicious software such as worms, viruses and Trojans, it refers to the software’s harmful results. Examples of payloads include data destruction, messages with insulting text or spurious e-mail messages sent to a large number of people.
In computer security, payload refers to the part of a computer virus which performs a malicious action