Glossary

YAML

YAML (YAML Ain't Markup Language) is a data serialisation format designed for human readability. Less punctuation than JSON; especially popular for configuration files (Docker Compose, GitHub Actions, Kubernetes, Ansible).

Syntax

name: icodelab
version: "1.0"
services:
  - name: web
    port: 80
    env:
      DEBUG: false
      DB_HOST: mysql
tags:
  - php
  - backend

YAML vs JSON

YAML supports comments (#); JSON does not
YAML is whitespace-sensitive — one wrong space can break everything
YAML is a superset of JSON: valid JSON is valid YAML

Pitfalls

YAML has the "Norway Problem": some strings are automatically coerced into types. yes/no → true/false; NO (Norway country code) → false. Always quote string values.