Ansible is an agentless configuration management and provisioning tool that is easy to use and secure. It uses an inventory file to define hosts and groups, and facts to gather information about hosts. Playbooks are written in YAML format to define tasks like provisioning, deploying applications, and configuration using modules. Playbooks can include roles and tasks. Ansible has over 250 modules for various tasks like packaging, source control, cloud services, and operating system functions. Additional tools include Vault for encrypting variables and Galaxy for sharing roles.