export const metadata = {
  title: `${pageNumber} Commerce Modules`,
}

# {metadata.title}

In this chapter, you'll learn about Medusa's commerce modules.

## What is a Commerce Module?

Medusa provides all its commerce features as separate modules, such as the Product or Order modules.

These modules and your custom modules are interchangeable in the Medusa application, making Medusa’s architecture more flexible.

Refer to [this reference](!resources!/commerce-modules) for a full list of commerce modules in Medusa.

---

## Resolve Commerce Module Services

Similarly to your custom module, a commerce module's main service is registered in the Medusa container. So, you can resolve it in your resources, such as API routes, to use its functionality.

For example, you saw this code snippet in the [Medusa container chapter](../medusa-container/page.mdx):

```ts highlights={[["13"]]}
import type { MedusaRequest, MedusaResponse } from "@medusajs/medusa"
import { IProductModuleService } from "@medusajs/types"
import { ModuleRegistrationName } from "@medusajs/utils"

export const GET = async (req: MedusaRequest, res: MedusaResponse) => {
  const productModuleService: IProductModuleService = req.scope.resolve(
    ModuleRegistrationName.PRODUCT
  )

  const [, count] = await productModuleService.listAndCount()

  res.json({
    count,
  })
}
```

When you resolve the `ModuleRegistrationName.PRODUCT` (or `productModuleService`) registration name, you're actually resolving the main service of the Product Module.

<Note title="Tip">

To resolve the main service of any commerce module, use the registration name defined in the `ModuleRegistrationName` enum imported from `@medusajs/modules-sdk`.

</Note>