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A file type, commonly referred to as a file format, is the ending of a file that gives the operating system the ability to identify it. The file type specifies the relationship between the file and specific programs or applications, and tells a software application how to display it. In Microsoft Windows, the file type is a three-character suffix preceded by a period and the file's name. For example, a file named ”windows” with a “.ppt” file type is displayed as “windows.ppt.” The file type of “ppt” indicates to the computer’s operating system that it is a presentation file and can be opened and edited in presentation software such as Microsoft PowerPoint. In most cases, the file type will be one to three characters at the end of the file name. However, there are some software applications that allow for more than the traditional three-character file type, such as the “html” file type associated with web pages.
The file type of a document tells a program how to structure and display the contents of the file. As productivity application software has evolved, some file types have become associated with particular applications. Furthermore, manufacturers of software have also developed native file types. A native file type describes the file type that an application directly uses during the creation and editing of a document. For example, a file with the .doc or .docx file extension specifies to the computer’s operating system that the file will be best viewed with Microsoft Word. This is because the .doc file type is native to Microsoft Word.
Listed below is a table with common productivity software applications and their native file formats:
| Productivity Software Application | Common Native File Types |
|---|---|
| Microsoft Word | .doc, .docx, .rtf |
| Microsoft PowerPoint | .ppt, .pptx |
| Microsoft Excel | .xls, .xlsx |
| Microsoft Access | .accdb, .mdb |
In some cases, a file with a specific extension may be viewed with a piece of software not native — or foreign — to that extension. A foreign file type is a file type that is not directly used by an application during the creation or editing of a document. When opening documents with file formats foreign to a software application, the contents may not be displayed accurately or completely. Programs that are not compatible with a file format may be able to give an overview of a file, but they may not be able to display all of the file's features.
Remember that file formats define for software applications how the contents of a particular file are to be displayed. As you work with a computer, there may come a time in which you need to make a determination as to what file format will be best suited to display the type of data you will be working with, or the type of file you wish to create. There may even come an instance in which you need to make an association between a file type and the correct type of application to use to display the contents of the file. Listed below is a table with common data (file) types and the associated file:
| Data Type | File Extension |
|---|---|
| Text | .asc, .doc, .docx, .msg, .txt, .wpd, .wps |
| Sound | .aac, .au, .mid, .mp3, .ra, .snd, .wma, .wav |
| Image | .bmp, .eps, .gif, .jpg, .pict, .png, .tif |
| Database | .xml, .tar, .sql, .db, .dbf, .dat, .csv |
| Video | .avi, mpg, .mov, .wmv |
| Computer Program | .bat, .com, .exe |
| Presentation | .ppt, .pptx, .pps, .key, .odp |
| Spreadsheet | .xls, .xlsx, .xlr, .ods |
Source: Derived from Chapter 3 of “Information Systems for Business and Beyond” by David T. Bourgeois. Some sections removed for brevity. https://www.saylor.org/site/textbooks/Information%20Systems%20for%20Business%20and%20Beyond/Textbook.html
