FILE NAME AND EXTENSION

• What is a computer file? a computer file—or simply a file—is defined as a named collection of data that exists on a storage medium, such as a hard disk, CD, DVD, or USB flash drive.

• A file can contain a group of records, a document, a photo, music, a video, an e-mail message, or a computer program.

• When you use word processing software, the text you enter for a document is stored as a file. You can give the file a name, such as A History of My Village.

• What are the rules for naming files? Every file has a name and might also have a file extension. When you save a file, you must provide a valid file name that adheres to specific rules, referred to as file-naming conventions.

• Each operating system has a unique set of file-naming conventions. Figure 1 lists file-naming conventions for the current versions of Windows and Mac OS.

• What are the rules for naming files?

• Is there a maximum length for file names? DOS and Windows 3.1 limited file names to eight characters, it was thus difficult to create descriptive file names.

• With such naming limitation, it was not always easy to figure out what a file contained. As a result, files were sometimes difficult to locate and identify. Today, most operating systems allow you to use longer file names.

• Current versions of Windows and Mac OS support file names up to

255 characters long. In practice, some of the 255 characters are used for the file’s drive letter, folder designation, and extension, so the name you assign to a file should typically be quite a bit shorter.

• What is a file extension? A file extension (sometimes referred to as a file name extension) is an optional file identifier that is separated from the main file name by a period, as in Paint.exe.

• As you become familiar with file extensions, they will provide a clue to the file’s contents. Files with .exe extensions are executable files that your computer can run.

• Paint.exe, for example, is a graphics utility packaged with the Windows operating system. Files with .dat extensions are typically data files. Files with .doc or .docx extensions contain word processing documents.

• Why are certain characters not allowed in a file name? If an operating system attaches special significance to a symbol, you might not be able to use it in a file name.

• For example, Windows uses the colon (:) character to separate

the device letter from a file name or folder, as in C:Music.

• A file name that contains a colon, such as Report:2010, is not valid because the operating system would become confused about how to interpret the colon.