information technology Information technology (IT) is a set of related fields within information and communications technology (ICT), that encompass computer systems, software, programming languages, data processing, data and information processing, and storage. Inf ...

, a trailer or footer refers to supplemental

data Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...

(

metadata Metadata (or metainformation) is "data that provides information about other data", but not the content of the data itself, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive ...

) 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. 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 Parsing, syntax analysis, or syntactic analysis is a process of analyzing a String (computer science), string of Symbol (formal), symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal gramm ...

. 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

Examples

* In data transfer, the

OSI model The Open Systems Interconnection (OSI) model is a reference model developed by the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems inter ...

's data link layer adds a trailer at the end of frames of the data encapsulation.

References

Computer data {{compu-storage-stub