# Lifecycle

the order node hooks fire, made visible.

```{raw} html
<a class="example-run-button" href="../demos/features_basics_lifecycle.html">▶ Run in browser</a>

```

**Tags:** `basics` `lifecycle` `node`

Every node runs through the same hooks in the same order: `on_enter_tree`
when it is attached to the running tree, `on_ready` once right after, then
`on_update(dt)` every frame, and `on_exit_tree` when it leaves. Here a child
node is spawned and later removed on a timer, and each hook appends to a shared
log so the firing order is plainly readable on screen.


## What it demonstrates

- Hook order: `on_enter_tree` -> `on_ready` -> `on_update(dt)` (every frame) -> `on_exit_tree`.
- `on_enter_tree` / `on_exit_tree` bracket a node's time in the tree; `on_ready` fires exactly once.
- `on_update(dt)` runs once per frame while the node is in the tree.
- Removing a child (`remove_child`) fires its `on_exit_tree`.

## Source

```{literalinclude} ../../examples/features/basics/lifecycle.py
:language: python
:linenos:
```