> ## 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.

# Resolve Anonymous Visitors to Customers

> Match anonymous browsing sessions to known customers for better ad targeting and attribution.

Most store visitors browse anonymously until they log in or enter an email at checkout. Without identity resolution, each anonymous session looks like a different person — your attribution fragments, retargeting audiences shrink, and conversion APIs receive events with weak match signals.

Identity resolution stitches anonymous sessions to known customers. A visitor browses your store, adds to cart, leaves — then returns and completes checkout with their email. Upstack ID links that checkout identity to all prior anonymous events in the session and across devices. Suddenly Meta, TikTok, and Klaviyo can match conversions to the right profiles.

Why it matters for ad platforms: higher match rates mean better optimization, larger retargeting pools, and more accurate ROAS. Upstack ID typically increases identified sessions by 30–60% compared to cookie-only tracking.

<Tip>
  Identity resolution happens automatically after you install the pixel and connect destinations. Upstack ID uses deterministic matching (email, phone, Shopify customer ID) and session stitching to link anonymous events to known customers.
</Tip>

## How to set this up

<CardGroup cols={2}>
  <Card title="Identity Resolution" icon="fingerprint" href="/pixel/identity-resolution">
    How Upstack ID connects anonymous sessions to known customers.
  </Card>

  <Card title="Identity Resolution (Data Dictionary)" icon="table" href="/pixel/identity-resolution">
    Fields and semantics for resolved identity.
  </Card>

  <Card title="Identity Stitching" icon="link" href="/pixel/identity-stitching">
    How events are retroactively attributed within sessions.
  </Card>
</CardGroup>

## Related Articles

<CardGroup cols={2}>
  <Card title="Data Enrichment" href="/concepts/data-enrichment" />

  <Card title="Destinations Overview" href="/destinations/overview" />

  <Card title="Improve Meta Match Quality" href="/use-cases/improve-meta-match-quality" />

  <Card title="Recover Abandoned Carts" href="/use-cases/recover-abandoned-carts" />
</CardGroup>