---
title: fn::concat
url: /docs/esc/concepts/builtin-functions/fn-concat/
---
The `fn::concat` built-in function concatenates two or more arrays.

## Declaration

```yaml
fn::concat: array-of-arrays
```

### Parameters

| Property          | Type   | Description                                                       |
|-------------------|--------|-------------------------------------------------------------------|
| `array-of-arrays` | array  | The arrays to concatenate.

### Returns

A new array that concatenates those passed as arguments.