# Nodes

Every node has inputs on the left side and outputs on the right side.

There are 2 types of nodes: action nodes and basic nodes.

## **Action nodes**

They have at least one lifeline (lime color) square pin input or output.

<div align="left"><img src="https://3312042618-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9sVaJpWJhPbmscipukhh%2Fuploads%2Fgit-blob-b3a1debf341fd74d38c0f897cb34c4ba58302fa1%2FActionNode.png?alt=media" alt=""></div>

There are **3 special action nodes** in every layer. They are inserted by default.

<div align="left"><img src="https://3312042618-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9sVaJpWJhPbmscipukhh%2Fuploads%2Fgit-blob-270fef9474e621208e0b03ea4e6b719ac7231201%2F3SpecialNodes.png?alt=media" alt=""></div>

* **Tick** node executes every frame as long as the transport (the green vertical line in the Timeline indicating where in the Section you are) is on the layer.
* **On Begin** executes only once when this layer first become active. Usually this happens when the playhead touches the left side of the layer.
* **On End** is similar to On begin, except that it executes at the end of the layer.

## **Basic nodes**

They have no square lime Lifeline pin inputs or outputs.

<div align="left"><img src="https://3312042618-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9sVaJpWJhPbmscipukhh%2Fuploads%2Fgit-blob-4ccae5a9a7a76fba9a19f09117cab99a2d67ec23%2FBasicNode.png?alt=media" alt=""></div>

### Node controls

#### Preview

Some nodes also contain a **Preview** option. Toggle it on or off with a **Preview** icon.

<div align="left"><img src="https://3312042618-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9sVaJpWJhPbmscipukhh%2Fuploads%2Fgit-blob-9ca97d98aa52e0d692d8d7a501ba0c13228dd920%2FNodes_Preview.gif?alt=media" alt=""></div>

#### Bypass

<div align="left"><img src="https://3312042618-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9sVaJpWJhPbmscipukhh%2Fuploads%2Fgit-blob-55702c61890619af89d1936a47566228e92922b0%2FBypassIcon.gif?alt=media" alt=""></div>

Bypass icon causes the node to not execute at all.

{% hint style="info" %}
**Good to know**: Bypass is useful, especially with various texture processing nodes.
{% endhint %}