Filenames, file formats, and types Edit

Naming files

Use lowercase file, folder, and directory names. In general, separate words in filenames with hyphens, not underscores. Use standard ASCII alphanumeric characters in file, folder, and directory names.

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Consistent naming

If you’re creating and naming new files where other files have a different naming convention, see if the other files and folders can be renamed with the aforementioned guidelines. If you cannot change existing filenames, it is acceptable to use underscores or other naming conventions that are in use, to remain consistent with the existing style.

For example, if the directory already has files named as theme_1.php, theme_2.php, and theme_3.php, it’s acceptable to name the new file as theme_4.php instead of theme-4.php.

Examples

It’s acceptable to have some inconsistency in file and folder names if it can’t be avoided otherwise. There might be predefined design and style guidelines or undocumented guidelines that are already in use. Sometimes, file naming can also be automated by the product. In those cases, it’s okay to make exceptions for those files.

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Referring to files

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Referring to filenames

While referring to a file, follow these guidelines:

• Use code font.
• Use the exact name of the file, even if it doesn’t follow the file naming guidelines.
• If content from the file is included in the page, follow the code example guidelines and precede the code sample or content with an introductory statement that states the filename.

Example

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File interactions

While writing about file interactions, don’t use the file types as a verb.

Examples

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Referring to file types

Use the formal file type instead of the file extension while referring to file types. Many file types are expressed in uppercase, as they are acronyms or initialisms.

Examples

The following table lists filename extensions and the corresponding file type names to use:

Extension	File type name
.css	CSS file
.csv	CSV file
.dmg	DMG file
.exe	executable file
.gif	GIF file
.html	HTML file
.img	disk image file
.jar	JAR file
.java	Java file
.jpg, .jpeg	JPEG file
.js	JavaScript file
.json	JSON file
.md	Markdown file
.mp3	MP3 file
.mp4	MP4 file/MPEG-4 file
.pdf	PDF file
.php	PHP file
.png	PNG file
.ps	PowerShell file
.py	Python file
.rar	RAR file
.sh	Bash file
.sql	SQL file
.svg	SVG file
.tar	tar file
.txt	text file
.wav	WAV file
.xml	XML file
.yaml, .yml	YAML file
.zip	zip file

Last updated: April 6, 2021