> ## 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.

# Variants, categories & collections

> The native Medusa Product structure the shared catalog is built on.

In this document, you'll learn about the structural models that organize the
shared catalog, all of them native to Medusa's Product module.

## Product variant

A variant is a purchasable configuration of a master product, represented by the
`ProductVariant` data model (table `product_variant`, id prefix `variant`).
Variants are generated from a product's options, including Mercur attributes
marked as variant axes, and hold the SKU-level structure of the catalog entry.

```ts theme={null}
const { data: products } = await query.graph({
  entity: "product",
  fields: ["id", "title", "variants.id", "variants.title", "options.*"],
  filters: { id: "prod_123" },
})
```

<Note>
  Offer-based inventory and pricing live on the [offer](/platform/offer/overview),
  not the variant. The variant defines the shared catalog structure. Each store's
  stock and price come from its own offer.
</Note>

## Categories & collections

Products are organized with Medusa's native grouping models:

| Model               | Purpose                                                  |
| ------------------- | -------------------------------------------------------- |
| `ProductCategory`   | Hierarchical, nestable classification (id prefix `pcat`) |
| `ProductCollection` | Flat, curated grouping (id prefix `pcol`)                |
| `ProductTag`        | Free-form labels for filtering                           |
| `ProductType`       | A single type classification per product                 |

Assign products to a category with `assignProductsToCategoryWorkflow`, which
keeps each product in exactly one category at a time.

<Tip>
  Categories participate in the marketplace layer too: the `category_seller`
  link scopes which stores a category is associated with, mirroring the product
  [allowlist](/platform/catalog/concepts/product-seller-allowlist).
</Tip>