File Extensions TXT File Format SUMMARY: The TXT plain-text file format defined.   A file ending in ".TXT" usually designates that the file is a plain-text file. This can contain virtually any type of text - a recipe, documentation for software, a book report draft, or whatever. When a file ending in ".TXT" is double-clicked, a text editor, such as Notepad, should appear, allowing you to view and/or edit the contents of the file. Windows users: NOTE that unless you have configured your computer with the file extension viewing tweak, it is possible that a filename that looks like it ends with ".txt", especially one attached to an e-mail message, actually has a hidden OTHER extension, meaning that if you double-click the file, it may actually run a computer virus!   Add: Del.icio.us | Digg | Furl | My Yahoo!   Discuss This Tip Print This Tip Get E-Mail When New Tips are Online Return to the File Extensions page.