.YML File Extension
What is a YML file?
A YML 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. Because YAML syntax is language-agnostic, YML files can be incorporated into programs written in most popular programming languages, including C/C++, Ruby, Python, Java, Perl, C#, PHP, and others.
YML files are most commonly used as configuration files, which define a program or application's settings. If a program uses a YML file as a settings file, you can edit the program's settings by opening and editing the YML file in a text or source code editor. Most settings-related YML files include comments that explain how the file can be used to adjust a program's settings.
NOTE: YAML files are more commonly saved with the .YAML extension.
Common YML Filenames
database.yml - A YML file that Ruby on Rails uses to save connection information when connecting to a database.
How to open a YML file
You can open a YML file in any text editor, such as Microsoft Notepad (Windows) or Apple TextEdit (Mac). However, if you intend to edit a YML file, you should open it using a source code editor, such as Microsoft Visual Studio Code (cross-platform) or GitHub Atom (cross-platform). These applications provide helpful source code editing tools and highlight YAML syntax correctly.