YAML

Purpose

To provide a configuration format easier to write and maintain by hand than JSON, supporting comments, multiple documents, and anchor references.

Mechanism

Indentation (spaces, never tabs) expresses nesting, colons separate keys from values, and dashes mark list items. It supports comments (#), multiple documents (---), and anchors (&) with aliases (*) for reference. Watch out for type inference (yes/no becoming booleans).

Use cases

• CI/CD configuration (GitHub Actions, GitLab CI)
• Kubernetes manifests
• Docker Compose
• Application configuration files

Examples

• Input

  name: Ada
  age: 36

  Output

  The object {name:"Ada", age:36}

  Indentation expresses hierarchy

Common errors

Indenting with tabs (YAML allows spaces only)

Use spaces for indentation consistently