# Juju > Juju is an open source orchestration engine for deploying, integrating, and managing applications across Kubernetes, VMs, and bare metal using software operators called charms. 2026 CC-BY-SA, Canonical Ltd. ## Pages in this subsection - [Hook](https://documentation.ubuntu.com/juju/4.0/reference/hook.md): Juju hooks reference: charm lifecycle events, hook execution, idempotency, and Ops framework integration for application state management. ## Optional - [Top-level llms.txt](https://documentation.ubuntu.com/juju/4.0/llms.txt): Complete documentation index.