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

# How Signal works

> Follow the flow from linked accounts to conversion events, attribution, and audience building.

Signal turns eligible activity from linked retailer and marketplace accounts into conversion events for digital advertising platforms. You choose which events to send and where they go.

## From linked account to conversion event

<Steps>
  <Step title="A consumer links an account">
    The consumer connects a supported retailer or marketplace account to your brand through [Subtotal Link](/docs/subtotal-link/introduction). Linking creates an event that your brand can choose to treat as a conversion.
  </Step>

  <Step title="Subtotal collects shared purchases">
    Subtotal collects available purchases from the linked account and identifies items matching your brands. Eligible purchases can produce purchase-sharing events.
  </Step>

  <Step title="Signal checks eligibility and sends events">
    Signal applies consumer opt-outs, access rules, and your destination settings, along with the integration's delivery requirements. It sends eligible events to the advertising platforms you configure.
  </Step>

  <Step title="Use the signals in your advertising platform">
    The destination platform processes events for matching and attribution. Depending on its supported features and your configuration, you can also use them for campaign optimization, custom audiences, and lookalike seeds.
  </Step>
</Steps>

For the meaning and potential uses of each event, see [Conversion events](/docs/subtotal-signal/introduction#conversion-events).

## Event eligibility

A purchase appearing in Subtotal does not automatically mean it will be sent to an advertising platform. Delivery depends on access to the purchase, connection state, consumer choices, destination configuration, and platform-specific requirements such as event age and available matching information.

Before enabling Signal, [connect your opt-out process to Subtotal](/docs/subtotal-signal/opt-outs). Coverage depends on the accounts consumers link and the data available from supported retailers and marketplaces.

## Delivery, matching, and attribution

These stages answer different questions:

| Stage      | What it tells you                                                                       |
| ---------- | --------------------------------------------------------------------------------------- |
| Delivered  | The advertising platform accepted the event request.                                    |
| Matched    | The platform associated the supplied identifiers with a person.                         |
| Attributed | The platform credited a conversion to an ad interaction under its attribution settings. |

Signal sends eligible events without first establishing that an ad caused them. The advertising platform determines which events can be matched and attributed. A received event may therefore appear in event reporting without appearing as an attributed conversion in campaign reporting.

Attribution describes how the platform assigns credit. Use an appropriate controlled test to evaluate incremental sales or improvements in campaign performance.

## Configure an integration

Each integration guide covers its event names, data fields, delivery limits, and setup.

Start with [Meta setup](/docs/integrations/meta/introduction), or explore [Meta events and data](/docs/integrations/meta/events).