Ansible is useful as a command-line tool for making small changes. However, its real power lies in its scripting abilities. While setting up machines, you almost always need to do more than one thing at a time. Ansible provides for this by using a tool called playbook. Using playbooks, you can perform many actions at once, and across multiple systems. They provide a way to orchestrate deployments, ensure a consistent configuration, or simply perform a common task.
Playbooks are expressed in YAML, and for the most part, Ansible uses a standard YAML parser. This means that you have all the features of YAML available to you as you write them. For example, you can use the same commenting system as you would in YAML. Many lines of a playbook can also be written and represented in YAML data types. See http://www.yaml.org/ for more information.
Playbooks also open up many opportunities. They allow you to carry the state from one command to the next. For example, you can...