According to Wikipedia:
YAML (/ˈjæməl/) is a human-readable data-serialization language. It is commonly used for configuration files and in applications where data is being stored or transmitted. YAML targets many of the same communications applications as Extensible Markup Language (XML) but has a minimal syntax which intentionally differs from Standard Generalized Markup Language (SGML). It uses both Python-style indentation to indicate nesting, and a more compact format that uses
[...]
and{...}
for maps thus JSON file are valid YAML files.
#
character-
followed by a space, the value and separated by newlineskey: value
|
or...>
the whitespace/newlines.