In information technology, a trailer or footer refers to supplemental data (metadata) placed at the end of a block of data being stored or transmitted, which may contain information for the handling of the data block, or simply mark the block's end.[1]

In data transmission, the data following the end of the header and preceding the start of the trailer is called the payload or body.

It is vital that trailer composition follow a clear and unambiguous specification or format, to allow for parsing. If a trailer is not removed properly, or part of the payload is removed thinking it is a trailer, it can cause confusion.

The trailer contains information concerning the destination of a packet being sent over a network so for instance in the case of emails the destination of the email is contained in the trailer



  1. ^ Ambarisha Malladi; M. Chandra Naik; Sayyed Nagul Meera (2013). "Enhanced Packet Delivery Techniques Using Crypto-Logic on Jamming Attacks for Wireless Communication Medium" (PDF). International Journal of Computer & Organization Trends. 3 (4): 109. ISSN 2249-2593. S2CID 18200687. Archived from the original (PDF) on March 9, 2017.