import_playbook can be used to import one playbook into another playbook. A command uses of this is to have a master parent playbook that performs plays from child playbooks, like this.

- import_playbook: child.yml

Or like this.

- name: first child playbook
  import_playbook: child.yml

import_playbook cannot be run inside a task. For example, this would not work. include_tasks can be used to run a playbook within tasks.

- hosts: all
  tasks:
    import_playbook: child.yml