Playbooks are the basis of configuration management, and orchestrated automation with Ansible, and are designed for automating repeatable tasks.
Playbooks are expressed in YAML and have a minimum amount of syntax. YAML is a model of a configuration or a process. Because playbooks define a process and/or configuration, they are kept in source control.
Each playbook is composed of one or more plays. A play starts by defining the hosts line. The hosts line is a list of one or more groups or host patterns separated by colons.
Optionally, you can define the user to run the play as.
The hosts line is followed by a tasks list. Ansible executes tasks in order, one at a time, ...