File types and extensions

File types and extensions refer to closely-related concepts with different uses:

• File type, or file format, refers to the specific way that information is organized and encoded for storage in a computer file. In text, file type names are often abbreviated into initialisms or acronyms, such as PNG for Portable Network Graphics files.
• File extensions are suffixes added to the name of a file to indicate the file type. For example, a PNG file uses the .png extension. File extensions don't always match the exact letters of the file type, such as .docx for Microsoft Word files.

In general, use the following guidelines to determine whether to use the file type or file extension in your documentation:

• Use the file type when referring to the general category or classification of a file, such as JPG, PNG, or MP3.
• Use the file extension when specifically referring to the suffix at the end of the file name that denotes its format, such as .jpg, .docx, or .mp4.

File types

Write file types in regular font with appropriate capitalization. When using the acronym form, use all caps. If you need to spell out the file type in full, then use title case. Add a lowercase "s" to acronyms to use the plural form.

Example file types
This feature supports JPEG, PNG, and GIF file types.
The system supports various document file types, including PDFs and Word files.
Choose an MP3 file to upload.

File extensions

Write file extensions for file types in regular font. Include the preceding period.

If you need to use an indefinite article ("a" or "an"), write the one that applies to the sound of the first letter of the extension in American English, as though the period (or dot) is not announced. You don't need to format file extensions in monospaced font.

Example file extensions
To run the game, open the .exe file.
The image file must have the .png, .jpg, or .bmp file extension.
Ensure that the file has an .mp3 file extension.