Files

A file is a semi-permanent, named collection of information.

• semi-permanent: Files are usually stored on magnetic disk where they will remain for years even when the power is off. Of course, a file can be deleted (sometimes by accident) so they are semi-permanent, not permanent.
• named: A file has a name that is used to find it when it is needed. You probably know that MS Windows file names look like:
  • mydata.txt
  • program1.java
  • program1.class
  • doom.exe
  • ... and so on
• collection of information: The purpose of a file is to contain a collection of related information, such as a word processing document, a program source file, a spread sheet, a data base, and so on.

Notice that this is a conceptual definition of what a file is. It says what a file is and how it is used. A file can be implemented in many ways: as sections of a hard disk, as sections of a floppy disk, as part of a magnetic tape, and in other ways.