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What is a YAML file?
A YAML file is a text document that contains data formatted using YAML (YAML Ain't Markup Language), a human-readable data format used for data serialization. It is used for reading and writing data independent of a specific programming language. YAML files are often configuration files, used to define the settings of a program or application.
Because the YAML format is not language-specific, YAML files can be included and referenced within programs written in any language that supports YAML libraries, such as C/C++, Ruby, Python, Java, Perl, C#, and PHP. The YAML acronym originally stood for Yet Another Markup Language, but as the YAML format evolved, the acronym adopted its current, recursive meaning.
If a program uses a YAML file as a settings file, you can edit the program's settings by opening and editing the YAML file in a text or source code editor. Most settings-related YAML files include comments that explain how the file can be used to adjust a program's settings.
NOTE: While the programmer community recommends saving YAML files with the YAML extension, you might also encounter YAML files saved using the .YML extension.
Common YAML Filenames
app.yaml - A YAML file used by Google App Engine.
How to open a YAML file
You can open a YAML file in any text editor, such as Microsoft Notepad (Windows) or Apple TextEdit (Mac). However, if you intend to edit a YAML file, you should open it using a source code editor, such as NotePad++ (Windows) or GitHub Atom (cross-platform). These applications provide helpful source code editing tools and highlight YAML syntax correctly.