File Extension
The file extension specifies the type of file (document, image, video, etc.) and the format in which it is saved. The file extension also determines the default program used to open the file. It should accurately reflect the actual file type and should not be changed.
| Typ | File Extension |
| Text document | .doc, .docx, .odt, .ott, … |
| Spreadsheet | .xls, .xlsx, .ods, .ots, … |
| Presentation | .ppt, .pptx, .odp, .otp, … |
| PDF document | |
| Plain text file | .txt |
| Image file | .jpg, .jpeg, .png, .gif, .bmp, … |
| Video file | .mp4, .mkv, .webm, .avi, .wmv, .3gp, … |
| Audio file | .mp3, .wma, .aac, .flac, … |
| Website | .htm, .html, .xhtml, … |
| .eml |