information technology Information technology (IT) is the use of computers to create, process, store, retrieve, and exchange all kinds of data . and information. IT forms part of information and communications technology (ICT). An information technology syste ...

, a trailer or footer refers to supplemental

data In the pursuit of knowledge, data (; ) is a collection of discrete values that convey information, describing quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpret ...

(

metadata Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the 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 Payload is the object or the entity which is being carried by an aircraft or launch vehicle. Sometimes payload also refers to the carrying capacity of an aircraft or launch vehicle, usually measured in terms of weight. Depending on the nature of ...

or body. It is vital that trailer composition follow a clear and unambiguous specification or

format Format may refer to: Printing and visual media * Text formatting, the typesetting of text elements * Paper formats, or paper size standards * Newspaper format, the size of the paper page Computing * File format, particular way that informatio ...

, to allow for

parsing Parsing, syntax analysis, or syntactic analysis is the process of analyzing a string of symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal grammar. The term ''parsing'' comes from ...

. 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 model (OSI model) is a conceptual model that 'provides a common basis for the coordination of SOstandards development for the purpose of systems interconnection'. In the OSI reference model, the communications ...

data link layer The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer p ...

adds a trailer at the end of frames of the data encapsulation.

References

Computer data {{compu-storage-stub