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YAML Basics


Basic Concept

  • YAML is not a Markup Language
  • YAML is used to store a variety of information
  • It allows us to define key-value pairs like variables, lists, and objects
  • YAML is very similar to JSON (Javascript Object Notation)
  • Its primary focus is on readability and user friendliness
  • YAML is designed to be clean and easily readable
  • YAML files can be defined with two different extensions: .yml or .yaml

YAML – Key Value Pairs

  • YAML documents consist of key-value pairs.
  • The key and value are separated by a colon.
  • There must be a space after the colon to differentiate the value.
  • YAML supports various data types such as:
  • Integer
  • Floating-point numbers
  • Strings
  • Boolean
  • Dates (in ISO 8601 format)
  • Null values
  • Important Note
Name: Dave
Age: 29
Gpa: 4.2
Occupation: Engineer
State: 'New Jersey'
AboutMe: "I am a software engineer"
Male: true
DateOfBith: 1990-09-15T15:53:00
PoliceCases: null

YAML – List / Array

  • YAML lists are indented with an opening dash.
  • The dash indicates that it’s an element of an array.
  • All members of a list begin at the same indentation level, starting with a “-” (a dash and a space).
  • Block sequences indicate each entry with a dash and space.
  • Flow sequences are written as comma-separated lists within square brackets.
Block Sequence
- Dave
- John
- Mike
- Sam
Flow Sequence
Persons: [Dave, John, Mike, Sam]

YAML Dictionary / Map

  • YAML dictionaries are sets of properties grouped under an item.
  • YAML dictionaries contain key-value pairs.
Age: 25
Occupation: Engineer
State: New Jersey
gpa: 4.5
male: true

YAML Lists containing Dictionaries


YAML Lists containing Dictionaries containing Lists



  • The pipe notation, also known as a literal block.
  • All new lines, indentations, and extra spaces are preserved exactly as they are.
  Age: 25
  Address: |
    201 A St.
    New York 10000

YAML Greater than Sign

  • The “greater than” sign notation is also known as a folded block.
  • This renders the text as a single line.
  • All newline characters are replaced with a single space.
  • Blank lines are converted into newline characters.


YAML Comments

  • We can have comments in YAML with # sign.
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