YAML Cheatsheet

Basics

YAML stands for “YAML Ain’t Markup Language.” It uses indentation (spaces, not tabs) to represent structure. Data is written as key–value pairs.

name: Alice
age: 25
city: Paris

Indentation

Indentation defines hierarchy. Use **spaces only**, not tabs. Children must be indented more than their parent.

person:
  name: Alice
  age: 25

Lists

Lists are written with dashes (-). Each item appears on a new line with the same indentation.

fruits:
  - apple
  - banana
  - cherry

Dictionaries (Maps)

Dictionaries store key–value pairs. They are like JSON objects, but use colons instead of braces.

person:
  name: Alice
  age: 25

Nested Structures

Lists and dictionaries can be nested inside each other. This is how you build complex structures.

people:
  - name: Alice
    age: 25
  - name: Bob
    age: 30

Comments

Use # for comments. Comments are ignored by the computer but help humans understand the file.

# This is a comment
name: Alice

Multi-line Strings

Use | for multi-line text (preserves line breaks). Use > for folded text (joins into one line).

description: |
  This is line 1
  This is line 2

Anchors & Aliases

Anchors (&) let you reuse content. Aliases (*) refer back to anchors.

defaults: &defaults
  country: France

person:
  name: Alice
  <<: *defaults

How to use this page

1. Start with basics: key–value pairs and indentation.
2. Learn lists and dictionaries to represent structured data.
3. Use comments and multi-line strings for readability and docs.
4. Practice anchors & aliases to avoid repeating yourself.