What is YAML?

YAML is a simple, human readable format for representing associative and hierarchical data.

Example from wikipedia page on YAML:

receipt: Oz-Ware Purchase Invoice
date: 2012-08-06
customer:
  first name: Harry
  family name: Potter
address: |-
  4 Privet Drive,
  Little Whinging,
  England
items:
- part_no: A4786
  description: Water Bucket (Filled)
  price: 1.47
  quantity:  4

- part_no: E1628
  description: High Heeled "Ruby" Slippers
  size: 8
  price: 133.7
  quantity: 1

Key features:

• Things which are associated with other things - delimited by the colon (:).
• Ordered lists of things - delimited by the prepended dash (-).
• Multi-line strings - delimited by the bar (|) if there is another newline at the end of the string, or bar + dash (|-) if not.
• Indentation describing the hierarchy of data.
• Maps directly to data types common to most high level languages - lists, dicts, scalars.

You don't need to know much more than this.