Ansible is one of the newest and hottest open source configuration management tools. It has become increasingly popular due to its ease of use. One of the main differences with Chef and Puppet is the lack of any agent installed on the machine to configure. The only requirement is that the machine has Python preinstalled, which is most often the case anyway.
Ansible is executed via SSH. You can run ad-hoc commands to execute trivial scripts on servers, as well as apply Ansible playbooks - definitions of server configuration written in YAML format, analogous to Chef cookbooks and Puppet modules. Ansible needs an inventory file to be able to run a playbook or ad-hoc commands. An inventory is just a text ...
