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

# Glossary

> Glossary of Upstack Data terminology — attribution, CAPI, identity resolution, destinations, server-side tracking, and other concepts referenced throughout the documentation.

| Term                     | Definition                                                                                                                                                      |
| ------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Attribution**          | The process of assigning credit for a conversion to one or more marketing touchpoints.                                                                          |
| **CAPI**                 | Conversions API — a server-to-server integration for sending events to ad platforms (Meta, TikTok, etc.) without relying on browser cookies.                    |
| **Click ID**             | A unique identifier appended to URLs by ad platforms (e.g., `fbclid` for Meta, `ttclid` for TikTok, `gclid` for Google) used to match conversions to ad clicks. |
| **Conversion**           | A completed action that represents business value, most commonly a purchase.                                                                                    |
| **Custom event**         | A merchant-defined event tracked via the Upstack JavaScript SDK, beyond the 13 standard events.                                                                 |
| **Destination**          | A third-party platform that receives enriched event data from Upstack (e.g., Meta CAPI, Klaviyo, GA4).                                                          |
| **EMQ**                  | Event Match Quality — Meta's score (0–10) indicating how well your server events can be matched to Facebook users. Higher EMQ = better ad optimization.         |
| **Enrichment**           | The process of augmenting raw events with additional data: product catalog details, UTM parameters, identity signals, and session context.                      |
| **Event**                | A structured record of a customer interaction — a pageview, add-to-cart, purchase, or any custom action.                                                        |
| **Identity resolution**  | Matching anonymous visitor sessions to known customer profiles using deterministic (email, phone) and probabilistic (fingerprint, device) signals.              |
| **Identity stitching**   | Linking multiple sessions and devices belonging to the same person into a unified customer profile.                                                             |
| **Match rate**           | The percentage of server-side events that an ad platform can match to users on its network. Higher match rates improve ad optimization.                         |
| **PII**                  | Personally Identifiable Information — data like email and phone number. Upstack hashes PII (SHA-256) before sending to ad platforms.                            |
| **Pixel**                | A lightweight JavaScript snippet injected into your storefront that captures browser-side events and sends them to the Upstack edge API.                        |
| **ROAS**                 | Return on Ad Spend — revenue generated divided by ad spend. Upstack helps improve ROAS by providing higher-quality conversion data to ad platforms.             |
| **Server-side tracking** | Capturing events via server-to-server communication rather than browser-based JavaScript, making tracking resilient to ad blockers and cookie restrictions.     |
| **Source**               | A platform or integration that sends data into Upstack (e.g., Shopify storefront, Facebook Ads, Google Ads).                                                    |
| **Standard event**       | One of the 13 predefined event types that Upstack recognizes across all destinations (PageView, Purchase, AddToCart, etc.).                                     |
| **UTM parameters**       | URL query parameters (`utm_source`, `utm_medium`, `utm_campaign`, etc.) used to identify traffic sources and campaigns.                                         |
| **Webhook**              | An HTTP callback that delivers event data to an external URL in real time.                                                                                      |