# Product identifier

A product identifier is the client's unique stock keeping unit (SKU) for a product. A product's unique identifier is represented by an `id`. The product identifier value (`productID` or `PID`) is the identifier associated with a product. 

## Admin APIs and the product identifier

When you create a product programmatically or through [Global Commerce](https://gc.digitalriver.com/gc/ent/login.do), Digital River automatically assigns a product identifieDigital River assigns a product identifier when. 

The `productId` or `PID` variable can be one of the following values: an [individual](https://docs.digitalriver.com/commerce-api-references/admin-apis-reference/products#individual-product), [base](https://docs.digitalriver.com/commerce-api-references/admin-apis-reference/products#base-product), or product[ variation](https://docs.digitalriver.com/commerce-api-references/admin-apis-reference/products#product-variations) identifier. If you want to use your company's internal product identifiers,  see [External reference identifier (ERID)](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/product-external-reference-identifier-erid) for instructions.

## Shopper APIs and the product identifier

You can use a product identifier to search for a product or add a product to a cart. The following examples demonstrate how you can use the product identifier (`id`) with the product-related resource. If you want to use your company's internal product identifiers, see [External reference identifier (ERID)](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/product-external-reference-identifier-erid) for instructions.

### Retrieve specific products from the default catalog

The following request gets a product by its product identifier of `64578500`.

{% tabs %}
{% tab title="cURL" %}

```http
curl --location --request GET 
'https://api.digitalriver.com/v1/shoppers/me/products?id=64578500' \
--header 'Authorization: Bearer <API_key>' \
...
```

{% endtab %}
{% endtabs %}

### Add a product to a shopping cart using the external reference identifier

Using the `externalReferenceId` query parameter, the following request example adds a product to a cart.

{% tabs %}
{% tab title="cURL" %}

<pre class="language-json"><code class="lang-json">curl --location --request GET 
<strong>'https://api.digitalriver.com/v1/shoppers/me/carts/active/line-items?id=64578500' \
</strong>--header 'Authorization: Bearer &#x3C;API_key>' \
...
</code></pre>

{% endtab %}
{% endtabs %}

{% hint style="info" %}
If you do not provide a company identifier, The API uses the company identifier associated with the API key.
{% endhint %}

### Add a product by external reference identifier to the shopping cart and redirect to the storefront page

In a typical anonymous customer workflow, you can add products to a cart by external reference identifier, making a single POST call with a payload to the [Web Checkout](https://app.gitbook.com/s/X2fWaY1Kp5sXA1fmOL7z/cart/web-checkout#v1-shoppers-me-carts-active-web-checkout) resource. The following payload (request entity) adds a product with the `id`of `64578500`, with a `quantity` of `2`, to a cart.

{% tabs %}
{% tab title="Payload example" %}

```json
 {
   "webCheckout": {
     "cart": {
       "lineItems": {
         "lineItem": {
           "quantity": "2",
           "product": {
             "idd": "64578500"
            }
              ... more closing curly braces ...
```

{% endtab %}
{% endtabs %}

A successful request with this particular API results in a `302 redirect` to a Digital River-hosted guest checkout page.&#x20;