Data_(computing)

For other uses, see Data (disambiguation).

In computer science, data is any information in a form suitable for use with a computerdata. American Heritage Dictionary of the English Language. Retrieved on 2007-03-19.. Data is often distinguished from programs. A program is a set of instructions that detail a task for the computer to perform. In this sense, data is thus everything that is not program codedata. Webopedia. Retrieved on 2007-03-19..

In an alternate usage, binary files (which are not human-readable) are sometimes called "data", as distinguished from human-readable "text" file(1). OpenBSD Manual Pages (2004-12-04). Retrieved on 2007-03-19.. The total amount of digital data in 2007 was estimated to be 281 billion gigabytes.Paul, Ryan. "Study: amount of digital info > global storage capacity", Ars Technica, March 12, 2008. Retrieved on 2008-03-12. Gantz, John F. et al. (2008). The Diverse and Exploding Digital Universe. International Data Corporation via EMC. Retrieved on 2008-03-12.

Data vs programs

Fundamentally, computers follow the instructions they are given. A set of instructions to perform a given task (or tasks) is called a "program". In the nominal case, the program, as executed by the computer, will consist of binary machine code. The elements of storage manipulated by the program, but not actually executed by the CPU, contain data.

Typically, different files are used to store programs vs data. Executable files contain programs; all other files are data files. However, executable files may also contain data which is "built-in" to the program. In particular, some executable files have a data segment, which nominally contains constants and initial values (both data).

For example: A user might first instruct the operating system to load a word processor program from one file, and then edit a document stored in another file. In this example, the document would be considered data. If the word processor also features a spell checker, then the dictionary (word list) for the spell checker would also be considered data. The algorithms used by the spell checker to suggest corrections would be considered code.

The line between program and data can become blurry. An interpreter, for example, is a program. The input data to an interpreter is itself a program -- just not one expressed in native machine language. In many cases, the interpreted program will be a human-readable text file, which is manipulated with a text editor -- more normally associated with plain text data.

A more fundamental view

More fundamentally in programming, data is any evolving state. Code is a particular, very structured kind of data, which constitutes a way to specify what is being programmed. Code is specific in that it has a particular structure, imposed by the designer of the system which executes it. Sometimes, this structure is the only way to specify the behavior of a program. The notion that code is also data is harnessed in the design of functional languages to establish so-called expressive power.

References

See also

• Data
• Data (disambiguation)
• Data type
• Data segment

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