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

# Which ID goes where

> Tracking uses three different kinds of ids. Sending the right one in each event is what makes attribution work.

Depict tracking uses **three id vocabularies**. They look similar but are not interchangeable, and sending the wrong kind does not produce an error — the event is accepted and then silently fails to match anything, which quietly degrades your metrics. This page is the reference for which id each event needs.

| Event                          | Id to send                                                                             | Where it comes from                                                                                                                                                                                  |
| ------------------------------ | -------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Product card clicks            | **result id** (`search_result_id`, `recommendation_id` or `product_listing_result_id`) | Returned inside every display in our API responses. You place it on the card as a data attribute — see [Product Card Tracking](/api-guide/tracking/product-cards).                                   |
| `setProductId` (PDP views)     | **product id** (`product_id`)                                                          | The `product_id` field of the displays our API returns. It identifies the product on variant level — on Shopify this is the variant id.                                                              |
| `addToCart`                    | **product id** (`product_id`)                                                          | Same as `setProductId`. Use the id of the variant that was added.                                                                                                                                    |
| `purchase` → `items[].item_id` | **transaction product id**                                                             | The id your product data was ingested with for transaction matching. By default this is the SKU from your catalog; on Shopify it is the variant's SKU, or the variant id for variants without a SKU. |

## Why the difference matters

* **Result ids** are unique per API response, not per product — they tie a click to the exact search, listing or recommendation that produced it. That link is what powers surface-level performance metrics and lets ranking learn from real behaviour.
* **Product ids** join PDP views and add-to-carts to your catalog. If the id you send doesn't match the displays' `product_id`, those events can't be connected to products.
* **Transaction product ids** join purchase line items to your catalog through a mapping that is refreshed on every catalog ingestion. A line item whose `item_id` doesn't match drops out of per-product revenue, best-seller and funnel metrics — while still counting toward raw totals, which makes the gap easy to miss.

<Warning>
  The most common integration mistake is sending the displays' `product_id` as
  a purchase `item_id` (or vice versa). They are different vocabularies —
  purchases match on your SKUs, not on `product_id` — unless your catalog
  happens to use the same value for both.
</Warning>

## How to verify

The "Tracking status" tab on [app.depict.ai](https://app.depict.ai) shows your incoming events live. The table at the bottom lists examples of valid product ids from your ingested catalog — compare them against what your events are sending. After your first test purchases, confirm they map to catalog products rather than only appearing in raw event counts.