YAML is a human-readable data serialization language that is consistently listed as one of the most popular programming languages. It's often used as a format for configuration files, and in all kind of applications where data is being stored or transmitted. It uses both Python-style indentation to indicate nesting, and a more compact format for lists and associative arrays (also known as maps, dictionaries or hashes), making it a viable replacement for languages like JSON. The YAML acronym was shorthand for Yet Another Markup Language. But the maintainers have renamed it to YAML Ain't Markup Language to place more emphasis on its purpose as data-oriented, rather than document markup.