YAML - is language for serialization data to human-readable string. It is commonly used for configuration files (for example [ansible](https://docs.ansible.com/ansible/latest/user_guide/playbooks_intro.html), [kubernetes](https://kubernetes.io/docs/concepts/workloads/controllers/deployment/), [GItlab](https://docs.gitlab.com/ee/ci/yaml/), ...) YAML is more compact vs XML YAML supports data types: * string * integer * float * [associative arrays](https://en.wikipedia.org/wiki/Associative_arrays) YAML 1.2 is superset for JSON YAML example (this is ansible playbook): ``` - name: update web servers hosts: webservers remote_user: root tasks: - name: ensure apache is at the latest version yum: name: httpd state: latest - name: write the apache config file template: src: /srv/httpd.j2 dest: /etc/httpd.conf - name: update db servers hosts: databases remote_user: root tasks: - name: ensure postgresql is at the latest version yum: name: postgresql state: latest - name: ensure that postgresql is started service: name: postgresql state: started ```