File Formats

Overview Have you ever wondered just what the difference was between a .doc file and a .txt file? Or what about that .avi file that a friend e-mailed you and you don't even know if it's a document, a sound file, or something that contains a virus? Luckily, the Internet provides many resources for the enormous variety of file formats that exist. Due to the variety of both software and file formats, some Web sites with indexes of file formats may specialize in listing a specific type of file, such as graphics files or text file types. Other sites attempt to provide full lists of all known file formats. 

General Information If you are looking for additional information about file formats, this page provides a detailed beginnerís guide to file extensions. For a wide-ranging graphical file FAQ page, visit the Graphics File Formats FAQ page. Some file format Web sites, such as, provide valuable information about what type of files work with what software, and also provide freeware and shareware downloads of software that may help you open that mysterious file your aunt sent you. 

File Format Indexes Learning about file formats opens up a whole new perspective on the contents of a file. Valuable information is found just by viewing the fileís extension. However, it is difficult to memorize even a fraction of all the different file formats one may encounter. Fortunately, many Web sites list file formats that can be searched by software and file category, or by file extension. Visit this Web page to view an alphabetically sorted list of some of the more common file extensions and their corresponding file format, complete with a short description of each file type. For a more thorough list of file extensions, visit In addition to their internal search engine, this site categorizes their list by file type (e.g. sound and video, compression, and programming). 

Additional Links The Web page contains a small section of an extensive article about the FAT file system. Visit to view file format information that is geared towards programmers, providing details that are not found on many file format index sites.