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A CDE Definition

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computer file

See file.


A collection of bytes stored as an individual entity on the computer's hard drive or SSD. A file is the common denominator of storage. All data and programs, no matter which kind, are stored as files with an assigned file name that must be unique within the disk folder (directory) it resides in. Files with the same name can reside in separate folders. See folder.

Computers Know Nothing About Data Files
To the computer, a data file is nothing more than a string of bytes that is identified by name and location on the disk. Once read into the computer's memory, the structure of a file is known to the software that manipulates it. For example, database files are made up of a series of records (one per customer, vendor, transaction, etc.). Word processing files contain a continuous flow of text interspersed with format codes (tags). To learn more about file structures, see database.

Except for ASCII text files, which contain only raw text, other data files have proprietary structures. Formatting and descriptive information are contained in headers at the beginning of the file and/or in tags interspersed throughout the file.

Computers Are Savvy About Program Files
In contrast to data files, the computer is very aware of the content of an executable program file, which contains instructions. When given the starting point of an instruction in memory, the computer expects to find the strings of bytes in a machine instruction format that it recognizes and is able to follow, one instruction after the other (see machine language).

Following are the major file types. See file association, ASCII file, file system and files vs. folders.

 File Type       Contents

 data file       text & binary
  (table)         (rows/records)

 document        text & format codes

 spreadsheet     rows/columns of cells

 image           rows/columns of pixels

 drawing         list of vectors

 CD audio        digitized sound waves

  audio (MP3,    compressed digitized
  AAC, etc.)     sound waves

 MIDI            MIDI instructions

 video           digital video frames

 Web page        text, HTML tags &
  (HTML file)     JavaScript

 XML file        text

 batch file      text

 text file       text

 File Type       Contents

 source code     text

  language       binary (bytecode)

 executable      binary
  program         (machine language)

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