Definition

1. Noun:
   • A suffix appended to a computer filename: A file name extension is a sequence of characters, typically starting with a period (.), that follows the main part of a filename. It indicates the file's format or the type of data it contains, helping the operating system and software applications identify which program should be used to open it.

Usage

• The file name extension is a crucial part of a filename on many operating systems, especially Windows. It is separated from the main filename by a dot.
• Common examples include for plain text files, for image files, and for Portable Document Format files.
• While often hidden by default in modern operating systems for user simplicity, the extension remains a key technical identifier.

Examples

• Noun:
  • When you save a document, the application usually adds the correct file name extension automatically.
  • I couldn't open the file because I didn't have software for the .rar file name extension.
  • The file report.docx has the file name extension .docx, which signifies a Microsoft Word document.

Advanced Usage

• "Hidden extensions": A system setting where the file name extension is not displayed to the user in file browsers to reduce clutter, though the file still possesses it.
  • With hidden extensions enabled, a file named virus.txt.exe might appear as just virus.txt, which can be dangerous.
• "Default program association": The link between a specific file name extension and the application that opens it by default.
  • You can change the default program association for the .mp3 file name extension to your preferred music player.

Variants and Related Words

• Filename (n): The complete name of a file, which often includes the base name and the file name extension.
  • The filename presentation.pptx includes the extension .pptx.
• Extension (n): A common shortened form for "file name extension" in computing contexts.
  • What is the extension of that file?
• File format (n): The structure and organization of data in a file, often indicated by its extension.
  • The PDF file format is commonly associated with the .pdf extension.

Synonyms

• File extension: The most common direct synonym.
• Filename suffix: A more technical term describing its position in the filename.

Related Phrases

• To change the extension: To manually alter the characters after the dot in a filename.
  • Warning: Simply changing the extension does not convert the file's actual format; it might become unusable.
• To show/hide extensions: A command or setting within an operating system's file manager.
  • For better security, it's advisable to show file name extensions in Windows Folder Options.

Noun

1. a string of characters beginning with a period and followed by one or more letters; the optional second part of a PC computer filename
   • most applications provide extensions for the files they create
   • most BASIC files use the filename extension .BAS