Ansible playbooks are the core components of Ansible. Playbooks are written in YAML format and describe a set of tasks that need to be executed on the managed systems. A playbook consists of one or more plays, and each play defines a set of tasks to be performed on a group of hosts. Tasks are the individual actions or commands that Ansible should execute, such as installing packages, copying files, or restarting services. Tasks call out to the programmed code units called modules.