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YAML is a human-readable data serialization format used widely in configuration files, APIs, and automation workflows. But what exactly is YAML, and is there a difference between .yaml and .yml? Learn more about YAML vs YML.

What is YAML?

YAML (Yet Another Markup Language or YAML Ain’t Markup Language) is a lightweight and easy-to-read format designed for structured data representation. It is commonly used in DevOps, CI/CD pipelines, and cloud configurations due to its simplicity and flexibility. Explore test automation best practices.

Why Use YAML?

✅ Human-Readable Format – Uses indentation instead of brackets. ✅ Supports Complex Data Structures – Works with lists, dictionaries, and nested objects. ✅ Widely Used in DevOps & CI/CD – Used in Kubernetes, GitHub Actions, and Docker Compose. ✅ Compatible with Multiple Programming Languages – Works with Python, JavaScript, and more.

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YAML vs YML: What’s the Difference?

There is no functional difference between .yaml and .yml file extensions. YAML originally used .yml due to 3-character file extension limitations, but modern systems support .yaml as the preferred standard.

Feature .yaml .yml
Standard Usage ✅ ✅
Preferred for New Projects ✅ ❌
Historical Limitation ❌ ✅
Compatibility ✅ ✅

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YAML Syntax Basics

1. Key-Value Pairs 

name: Keploy
language: YAML
version: 1.0

2. Lists in YAML 

languages:
  - Python
  - JavaScript
  - Go

3. Nested Objects 

database:
  host: localhost
  port: 5432
  username: admin

Explore how YAML is used in CI/CD workflows.

Best Practices for Using YAML

✅ Use Consistent Indentation – Avoid tabs, use spaces. ✅ Keep It Simple – Avoid unnecessary complexity. ✅ Validate YAML Files – Use tools like yamllint. ✅ Avoid Tabs – Indentation should be with spaces only. ✅ Use Descriptive Keys – Maintain readability and structure.

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Where is YAML Used?

  • Kubernetes Configurations – Defining Pods, Services, and Deployments.

  • GitHub Actions – Automating workflows.

  • Docker Compose – Managing multi-container applications.

  • CI/CD Pipelines – Automating builds and deployments.

  • Infrastructure as Code (IaC) – Terraform and Ansible use YAML for automation.

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Conclusion

YAML is an essential format for modern development, especially in DevOps, CI/CD, and automation. Whether using .yaml or .yml, developers should focus on proper syntax, indentation, and validation to avoid errors. Explore more about YAML and its applications.

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