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
```
