Theme blocks support the `{% schema %}` Liquid tag. This tag is used to define the following block attributes and settings:

- [`name`](#name)
- [`settings`](#settings)
- [`blocks`](#blocks)
- [`presets`](#presets)
- [`tag`](#tag)
- [`class`](#class)

These attributes and settings enable different customization options and preconfigurations of the block inside the theme editor.

The following is an example of a block schema that opts-in to supporting nested blocks with its `block` attribute, defines some background-related `settings`, and assembles different variations of those settings with its `presets` attribute:


```json

{% schema %}
{
  "name": "Slide",
  "blocks": [{"type": "@app"}, {"type": "@theme"}],
  "settings": [
    {
      "type": "image_picker",
      "id": "image",
      "label": "Background image"
    },
    {
      "type": "color_background",
      "id": "background",
      "label": "Background color"
    }
  ],
  "presets": [
    {
      "name": "Slide",
      "settings": {
        "background": "#000000"
      },
      "blocks": [
        {
          "type": "text",
          "settings": {
            "text": "This is a slide!"
          }
        }
      ]
    }
  ]
}
{% endschema %}

```



Each block can have only a single `{% schema %}` tag, which must contain only valid JSON and can only use the attributes listed below. The schema tag can be placed anywhere within the block file, but it can’t be nested inside another Liquid tag. It doesn’t output its contents, or render any Liquid included inside it.

> Caution
> Having more than one `{% schema %}` tag, or placing it inside another Liquid tag, will result in an error.

## name

The `name` attribute determines the block title that's shown in the theme editor. For example, the following schema returns the following output:

```json

{% schema %}
{
  "name": "Slide"
}
{% endschema %}

```

![name example](/assets/themes/theme-editor/block-title-example.png)


### Showing dynamic block titles in the theme editor

In specific cases, the theme editor can display an input setting value as the title of a block in the theme editor sidebar. This can help merchants to identify and rearrange blocks in a section.

The theme editor checks [the `id` values](/docs/storefronts/themes/architecture/settings/input-settings#standard-attributes) of the settings in a block to determine the best one to use for the block title.

The theme editor uses settings with the following `id` values, in the following order of precedence:

1. `heading`
2. `title`
3. `text`

If a setting with a matching `id` value doesn't exist, then the block name is used as the title.

For example, the following block with a setting `id` of `text` displays in the sidebar with the title `Welcome to our store`.


```json
{
  "name": "Text",
  "settings": [
    {
      "type": "text",
      "id": "text",
      "default": "Welcome to our store",
      "label": "Content"
    }
  ]
}
```



## settings

You can create block-specific [settings](/docs/storefronts/themes/architecture/settings/input-settings) to enable merchants to customize the block with the `settings` object:


```json

{% schema %}
{
  "name": "Slide",
  "settings": [
    {
      "type": "image_picker",
      "id": "image",
      "label": "Background image"
    },
    {
      "type": "color_background",
      "id": "background",
      "label": "Background color"
    }
  ]
}
{% endschema %}

```



> Caution:
> All block setting IDs must be unique within each block. Having duplicate IDs within a block throws an error.

### Accessing block settings

Block settings can be accessed through the [`block` object](/docs/api/liquid/objects/block#block-settings). Refer to [Access settings](/docs/storefronts/themes/architecture/settings#access-settings) to learn more.

## blocks

Theme blocks can accept other app and theme blocks as children using the `blocks` attribute of their schema:

```json

{% schema %}
{
  "name": "Slide",
  "blocks": [{"type": "@app"}, {"type": "@theme"}]
}
{% endschema %}

```

The `"@app"` type denotes that this block accepts app blocks. [App blocks](/docs/storefronts/themes/architecture/blocks/app-blocks) enable app developers to create blocks for merchants to add app content to their theme without having to directly edit theme code.

The `"@theme"` type denotes that this block is compatible with other theme-defined blocks that live in the `/blocks` folder of the theme.

Theme blocks can also be made individually accessible by explicitly referencing them.


```json

{% schema %}
{
  "name": "Slideshow",
  "blocks": [{"type": "@app"}, {"type": "slide"}]
}
{% endschema %}

```





> Note
> Unlike sections, which can define blocks locally using the blocks attribute of their schema, Theme blocks can't define local blocks in the `blocks` attribute of their schema.

### Rendering nested blocks

You can render a block's child blocks by using the `{% content_for 'blocks' %}` Liquid tag:

```liquid

<div class="slide">
  {% content_for 'blocks' %}
</div>

```

In the example above, each block's content is outputted by the `{% content_for 'blocks' %}` tag in the order stored in the [JSON template](/docs/storefronts/themes/architecture/templates/json-templates).

> Tip
> Theme blocks can be nested up to 8 levels deep, excluding the section level.

## presets


Presets are predefined block configurations that merchants can select when adding blocks to a [JSON template](/docs/storefronts/themes/architecture/templates/json-templates). Presets help you quickly provide merchants with different layouts and use cases by adjusting block settings. Additionally, presets of a block may reference other child blocks and assemble them in any number of configurations.

Presets appear in the **Add block** picker as follows:

![add_block _example](/assets/themes/theme-editor/add-block.png)


| Number | Description |
| --- | --- |
| 1 | Presets appear alphabetically based on their `name` attribute. |
| 2 | Presets can optionally be grouped into collapsible categories using the `category` attribute. |
| 3 | Uncategorized presets are always displayed first. |


Block presets have the following attributes:

| Attribute | Description | Required |
| --- | --- | --- |
| `name` | The preset name displayed in the theme editor's **Add block** picker and sidebar, and is persisted in the JSON template when you add a block. | Yes |
| `category` | Groups related presets together in the theme editor's **Add block** picker. | No |
| `settings` | Default values for settings you want to pre-populate. Each entry includes the setting name and its value.  | No |
| `blocks` | Default blocks included in the preset. Each block entry must include a `type` attribute matching the block type, and a `settings` object formatted similarly to the `settings` attribute above. <br> Optionally, include a `name` attribute to display when merchants add the block in the editor. | No |

Here's an example of how presets are defined within a block schema, assuming that the theme also contains a text block located in the `/blocks/text.liquid` Liquid file:


```json

{% schema %}
{
  "name": "Slide",
  "blocks": [{"type": "@app"}, {"type": "@theme"}],
  "settings": [
    {
      "type": "image_picker",
      "id": "image",
      "label": "Background image"
    },
    {
      "type": "color_background",
      "id": "background",
      "label": "Background color"
    }
  ],
  "presets": [
    {
      "name": "Slide",
      "category": "Banners",
      "settings": {
        "background": "#000000"
      },
      "blocks": [
        {
          "type": "text",
          "settings": {
            "text": "This is a slide!"
          }
        }
      ]
    }
  ]
}
{% endschema %}

```



## tag

By default, when Shopify renders a block, it’s wrapped in a `<div>` element with a unique `id` attribute:

```html
<div id="shopify-block-[id]" class="shopify-block">
  // Output of the block content
</div>
```

If you don’t want to use a `<div>`, then you can specify which kind of HTML element to use with the `tag` attribute.

For example, the following schema returns the following output:


```json

{% schema %}
{
  "name": "Image",
  "tag": "picture"
}
{% endschema %}

```




```html
<picture id="shopify-block-[id]" class="shopify-block">
  // Output of the block content
</picture>
```



> Tip
> The `tag` attribute accepts any string up to a limit of 50 characters. It can also be used to render custom HTML elements.

### Rendering blocks without a wrapper

In some advanced use cases, you might want more control over the tag and the attributes that are passed to it. For example, dynamically setting a tag or class name based on the settings of the block. In these scenarios, you can render blocks without a wrapper by setting the `tag` attribute to `null`.

When the `tag` attribute is set to `null`, Shopify doesn't wrap the contents of the block in a wrapper element, and instead directly outputs the contents of the block.

> Warning
> Blocks that make use of `“tag”: null` should contain a single top level HTML tag within the same Liquid file. Only a single HTML element can be tagged with `{{ block.shopify_attributes }}`. This element should be the topmost HTML element in the file. This is important to allow the theme editor to move the entirety of the block's markup to a new index when merchants re-order blocks without leaving orphaned HTML elements.


```liquid

<{{ block.settings.tag }} class=”heading” {{ block.shopify_attributes }}>
  ...
</{{ block.settings.tag }}>

{% schema %}
{
  "name": "Heading",
  "tag": null,
  "settings": [
    {
      "type": "select",
      "id": "heading_size",
      "label": "Heading size",
      "options": [
        {
          "value": "h3",
          "label": "Small"
        },
        {
          "value": "h2",
          "label": "Medium"
        },
        {
          "value": "h1",
          "label": "Large"
        }
      ]
    }
  ]
}
{% endschema %}

```




```html
<h3 class=”heading”>
  ...
</h3>
```



For blocks to be compatible with the theme editor, the top level HTML element must be tagged with the `{{ block.shopify_attributes }}` Liquid tag. This adds the necessary data attributes for the block to be identified by the theme editor. Shopify's theme editor uses that attribute to identify blocks in its [JavaScript API](/docs/storefronts/themes/architecture/sections/integrate-sections-with-the-theme-editor#javascript-events).

> Note
> Shopify automatically adds this attribute for you when it renders the wrapper around blocks, but when the `tag` attribute is set to `null`, you must ensure that the top level HTML element of your block has this attribute for it to be compatible with the theme editor.

## class

When Shopify renders a block, it’s wrapped in an HTML element with the `shopify-block` class. You can append other classes by using the class attribute:


```json

{% schema %}
{
  "name": "Slide",
  "class": "slide"
}
{% endschema %}

```




```html
<div id="shopify-block-[id]" class="shopify-block slide">
  // Output of the block content
</div>
```