In Ansible, a playbook is is a YAML file containing the definition of how a server should look. In a playbook you define what actions Ansible should take to get the server in the state you want. Only what you define gets done.
This is a basic Ansible playbook that installs git on every host belonging to the
--- - name: Git installation hosts: web remote_user: root tasks: - name: Install Git apt: name=git state=present