> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mercurjs.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Global vs inline & filtering

> Catalog-wide attributes, product-scoped attributes, and storefront filtering.

In this document, you'll learn the difference between global and inline
attributes and how an attribute becomes a storefront filter.

## Scope

Every `ProductAttribute` is either **global** or **inline**, decided by its
`product_id` field:

| Scope  | `product_id` | Meaning                                                                                                             |
| ------ | ------------ | ------------------------------------------------------------------------------------------------------------------- |
| Global | `null`       | A catalog entry, reusable across any product, listed in the operator's attribute catalog                            |
| Inline | set          | A one-off attribute scoped to a single product, created from that product's form and hidden from the global catalog |

```ts theme={null}
// Global: reusable across the catalog
{ name: "Material", type: "single_select", values: [{ name: "Cotton" }] }

// Inline: scoped to one product, created as it's attached
{ title: "Gift wrap", type: "toggle", product_id: "prod_123" }
```

A global attribute is defined once and attached to many products. An inline
attribute is created in the same step it is attached and only ever describes that
one product. It is useful for the occasional one-off field that doesn't belong in
the shared vocabulary.

<Note>
  Attributes describe products in the **shared master catalog**. They are never
  owned by a store. A seller sells against a master product through an offer, and
  the product's attributes come from the catalog, not from the seller.
</Note>

## Filtering

An attribute with `is_filterable` set to `true` is exposed as a storefront
filter, letting shoppers narrow the catalog by its values. Leave it `false` for
descriptive-only attributes that shouldn't appear as facets.

<Tip>
  Filtering pairs naturally with variant axes: a filterable `multi_select` axis
  like Color both generates variants and lets shoppers filter by them. A
  descriptive `text` attribute like Care instructions is usually left
  non-filterable.
</Tip>