YAML == Yet Another Markup Language
Single quotes allow you put (with some limitations) any character in your string, similar to BASH these won’t be expanded but treated as literals, “\n” is returns just the string \n.
As with BASH, double quotes are expanded, so “\n” is returned as a line feed NOT a “\n” sequence.
To use yes and no literally, “Yes” and “No” need to be enclosed in quotes, single or double as appropriate. Otherwise they will be treated as the Boolean equivolent, TrueClass and FalseClass values.
Single and double quotes have different meanings in YAML (Similar to BASH). You should use quotes in YAML if your string contains special characters. These characters should use quotes:-
{, }, [, ], ,, &, :, *, #, ?, |. -, <. >, =, !, %, @, \.
Quotes are not needed if a character is surrounded by spaces, as an example an asterink ( * ) with spaces surounding it.
Quotes should be used if your character is part of a longer string. An example of this is CRON:- */10 * * * * to run every 10 minutes needs quotes (“*/10 * * * *”)