Plays
A playbook consists of one or more plays, which map groups of hosts to well-defined tasks. The preceding example contains three plays, each to configure one layer in the multitiered web application. Plays also define the order in which tasks are configured. This allows us to orchestrate multitier deployments. For example, configure the load balancers only after starting the web servers, or perform two-phase deployment where the first phase only adds this configurations and the second phase starts the services in the desired order.
YAML – the playbook language
As you may have already noticed, the playbook that we wrote previously resembles more of a text configuration than a code snippet. This is because the creators of Ansible chose to use a simple, human-readable, and familiar YAML format to blueprint the infrastructure. This adds to Ansible's appeal, as users of this tool need not learn any special programming language to get started with. Ansible code is self-explanatory...
