File Extensions DOC File Format SUMMARY: This defines the DOC file format, usually word processing files created from WordPerfect or Microsoft Word.   Files with an extension of ".DOC" are usually documents created from word processors, most notably WordPerfect or more-frequently Microsoft Word. DOC files can contain text, images, photos, or any other type of information commonly found in word processing documents. While most are safe to open, unfortunately some malicious DOC files can contain macro viruses that can do damage to your machine. Luckily, you can increase macro virus protection by using anti-virus software or changing word processor settings, including in Microsoft Word 2003. In rare instances, some people write plain-text files and save them as .DOC files. 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 ".doc", 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.