YAML (YAML Ain't Markup Language) is a human-friendly data serialization standard that is widely used for configuration files, data exchange between languages, and object persistence. It emphasizes readability and simplicity, making it significantly easier for humans to write and understand compared to more verbose formats like XML or even JSON for complex configurations. YAML files typically store data in a structured format using key-value pairs, lists (sequences), and scalars (strings, numbers, booleans). Its structure relies heavily on indentation to denote hierarchy, similar to programming languages like Python. Common use cases include configuration files for applications (e.g., Docker Compose, Kubernetes, Ansible playbooks), data serialization for inter-process communication, log files, and defining build pipelines in CI/CD systems. It supports various data types, anchors for data reuse, and allows for comments, which further enhances its readability and maintainability. While it can represent the same data as JSON, YAML often offers a more concise and visually appealing syntax, especially for deeply nested structures or when inline documentation through comments is beneficial. It has become a cornerstone in the DevOps and cloud-native ecosystems due to its balance of human readability and machine parsability.