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

# Key concepts

> Core Meum terminology used consistently across documentation.

Use these terms precisely. Do not interchange them.

## Invoice

A payment request created by a merchant. Has a unique ID, amount, currency, status, and hosted checkout URL. An invoice may have zero or one active quote at a time.

## Payment (blockchain transaction)

The on-chain transfer a customer sends to the checkout deposit address. Tracked separately from the invoice with its own status (`pending`, `completed`, `underpaid`, `overpaid`, `failed`).

## Origin transaction

The customer's inbound crypto payment to the deposit address (the token they pay with).

## Settlement transaction

The conversion and transfer of funds to the merchant's settlement wallet in the configured output asset (stablecoin).

## Payer wallet / refund address

The address the customer provides at checkout. Used for refunds if applicable. Required on checkout quote creation.

## Settlement wallet (payout wallet)

The merchant-configured wallet address where settled stablecoin is sent. Configured at organization or store level in Merchant Admin.

## Customer

A commerce identity linked to invoices via metadata (WooCommerce customer ID, email, etc.). Viewable in Merchant Admin under Customers.

## Webhook delivery

An HTTP POST from Meum to your endpoint when invoice status changes. Signed with HMAC v1.

## WooCommerce order

The WordPress order created at checkout. Linked to a Meum invoice via `_stablecoin_invoice_id` order meta.

## Related pages

* [Payment statuses](/payments/payment-statuses)
* [Glossary](/resources/glossary)