This example is designed to be used as a quick introduction to playbook structure that can easily fit on one slide deck that demonstrates how Ansible works.
This playbook assures the hosts in a group called "web" has the Apache web server (httpd) present and is started with a static custom home page. The hosts are presumed to be running a Red Hat family linux.
The playbook is intended for demonstration and instructional purpose. In reality it's too simplistic to be really useful. See examples/apache-basic-playbook for a more complete example using Apache.