# Concat

### What It Does

Combines two lists into a single list by joining them end-to-end. This is perfect for merging collections like color arrays, spacing scales, or any other grouped token sets.

### Inputs

| Name | Description                       | Type | Required |
| ---- | --------------------------------- | ---- | -------- |
| a    | The first list to combine         | List | Yes      |
| b    | The second list to add to the end | List | Yes      |

### Outputs

| Name  | Description                                      | Type |
| ----- | ------------------------------------------------ | ---- |
| value | The combined list with all items from both lists | List |

![Array Concat Example](https://3657049418-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fy0SFXZjN1sdgdxYM7QPE%2Fuploads%2F4KblYHudGadgjB2A9CMN%2FScreenshot%202025-04-17%20at%206.13.09%E2%80%AFPM.png?alt=media\&token=56fafc02-bd6e-41ab-b900-ab8145fce94f)

### How to Use It

1. Drag the Array Concat node into your graph.
2. Connect your first list (like `[Red, Blue]`) to the "a" input.
3. Connect your second list (like `[Green, Yellow]`) to the "b" input.
4. Run the graph—your output will be `[Red, Blue, Green, Yellow]`.

<figure><img src="https://3657049418-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fy0SFXZjN1sdgdxYM7QPE%2Fuploads%2FToVkac6UjAYgIOwmaaHC%2FCleanShot%202025-05-06%20at%2011.40.05%402x.png?alt=media&#x26;token=8bacb9e3-5134-4b70-a92b-e6d2c5bb36ba" alt=""><figcaption></figcaption></figure>

### Tips

* Both lists must be of the same type (e.g., both colors or both numbers).
* Use multiple Concat nodes to combine more than two lists.

### See Also

* [**Array Push**](https://documentation.tokens.studio/graph-engine/available-nodes/array/push): For adding just a single item to a list.
* [**Array Remove**](https://documentation.tokens.studio/graph-engine/available-nodes/array/remove): For removing items from a list.

### Use Cases

* **Combining Token Collections**: Merge a base set of tokens with extension sets (e.g., join core colors with accent colors).
* **Building Complete Scales**: Combine different parts of a scale (e.g., join negative and positive spacing values).
* **Theme Management**: Join multiple theme-specific token collections to create a comprehensive theme.