YAML

• Is a data definition/expression format.
• The data which we define is name & value pairs
• YAML File Extension => .yaml or .yml extension
• Refer Here for the official docs
• Structure of ansible playbook

---
- name: <describe your playbook here>
  tasks:
    - name: <what this task is about>
      <module>:
         <module-parameter-1>: <module-value-1>
         ..
         <module-parameter-n>: <module-value-n>
         state: <value (present)>
    - name: <what this task is about>
      <module>:
         <module-parameter-1>: <module-value-1>
         ..
         <module-parameter-n>: <module-value-n>
         state: <value (present)>

• Sample playbook

---
- name: install apache server
  become: yes
  hosts: all
  tasks:
    - name: install apache2 and update packages
      apt:
        name: apache2
        state: present
    - name: restart apache2
      service:
        name: apache2
        state: restarted