YAML Ain’t Markup Language

Human Writable Structured Data

---
  pie: Apple
  
  numbers:
  - 10
  - 3.141592653589
  - 6.673e-11
  
  # Does this person like pie?
  likes: true
  
  # Actually nothing
  nothing: null
  
  rhyme: |
    Little jack horner stuck in his thumb
    and pulled out a plumb
  ---

YAML is a backward compatible JSON replacement for use when a structured data format must be written and maintained by humans. However, YAML is horrible when a program needs to write it due to the human-friendly use of comments, tabs, whitespace, line returns, and such that make it so popular with those creating configuration files and flat-file database applications.