diff --git a/src/content/docs/tools/glossary/checkout.mdx b/src/content/docs/tools/glossary/checkout.mdx
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----
-title: Checkout
-description: A checkout defines how SumUp should collect a payment from a customer.
-sidebar:
- order: 40
----
-
-A Checkout is a request or session that tells SumUp to collect a specific
-amount in a specific currency. It connects the commercial intent represented
-by a [Sale](/tools/glossary/sale/) with payment processing.
-
-A Checkout commonly contains:
-
-- The amount and currency to collect
-- The merchant receiving the payment
-- A merchant-defined reference
-- Optional customer, expiration, redirect, and callback details
-- Its current status and any linked
- [Transactions](/tools/glossary/transaction/)
-
-A Checkout is not proof that payment succeeded. It can exist before any payment
-attempt and can remain `PENDING`, fail, or expire without a successful
-Transaction.
-
-## Checkout Types in the Public APIs
-
-The Developer Portal uses Checkout in two related payment flows:
-
-- The **Checkouts API** creates an online Checkout, processes it with a payment
- instrument, and retrieves its latest state. Start with
- [Create a checkout](/api/checkouts/create), then use a supported integration
- such as the [Payment Widget](/online-payments/checkouts/card-widget/) or
- [Hosted Checkout](/online-payments/checkouts/hosted-checkout/).
-- The **Readers API** creates a Checkout on a paired card reader. This starts an
- asynchronous in-person payment flow. See
- [Create a Reader Checkout](/api/readers/create-checkout).
-
-These resources have different endpoint shapes and lifecycles, but serve the
-same conceptual purpose: they coordinate how a payment should be attempted.
-
-## Typical Online Checkout Flow
-
-```mermaid
-sequenceDiagram
- autonumber
- participant App as Your backend
- participant API as Checkouts API
- participant UI as Payment UI
- participant Tx as Transaction record
-
- App->>API: Create checkout
- API-->>App: Checkout with PENDING status
- App->>UI: Provide checkout ID
- UI->>API: Process payment
- API->>Tx: Record payment attempt
- API-->>UI: Return result or next action
- App->>API: Retrieve checkout
- API-->>App: Latest status and linked transactions
-```
-
-For redirect-based payment methods or 3DS, processing can return a next action
-instead of a final result. Always use
-[Retrieve a checkout](/api/checkouts/get) from your backend to confirm the
-latest Checkout status.
-
-## Relationship to a Sale and Transaction
-
-- The **Sale** describes the items, taxes, discounts, customer, and other
- commercial context.
-- The **Checkout** carries the amount, currency, and instructions needed to
- attempt payment.
-- Processing the Checkout creates or updates a **Transaction**, which records
- the financial result.
-
-A newly created Checkout can have an empty `transactions` array. Payment
-processing attaches Transaction records as attempts occur. Use the Checkout to
-manage the payment flow; use the
-[Transactions API](/api/transactions/get) for transaction details, history,
-and post-payment operations.
diff --git a/src/content/docs/tools/glossary/sale.mdx b/src/content/docs/tools/glossary/sale.mdx
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----
-title: Sale
-description: A sale records what was sold and connects the commercial event to its payments.
-sidebar:
- order: 30
----
-
-A Sale is the commercial record of an exchange between a merchant and a
-customer. It answers **what was sold**, independently of how the customer paid.
-
-A Sale can contain business details such as:
-
-- Items and quantities
-- Taxes, discounts, and tips
-- Customer information
-- The sales channel, device, or location
-- The total amount and payment state
-
-A Sale can exist before payment, be paid by one or more
-[Transactions](/tools/glossary/transaction/), or use a payment method that does
-not require a SumUp Checkout. This makes a Sale broader than a payment record.
-
-## How Sales, Checkouts, and Transactions Relate
-
-Use these terms to describe different parts of the same flow:
-
-- **Sale**: what the customer is buying
-- **[Checkout](/tools/glossary/checkout/)**: the request or session used to
- collect an amount
-- **[Transaction](/tools/glossary/transaction/)**: the recorded outcome of a
- payment attempt or later financial operation
-
-```mermaid
-flowchart LR
- Sale["Sale
Items, taxes, discounts, customer"]
- Checkout["Checkout
Amount, currency, payment flow"]
- Attempt["Payment attempt
Online or in person"]
- Transaction["Transaction
Financial outcome"]
- Events["Later events
Refund, chargeback, payout"]
-
- Sale -->|Amount to collect| Checkout
- Checkout -->|Process online or start on a reader| Attempt
- Attempt -->|Creates a record| Transaction
- Transaction -.->|Updates the payment state| Sale
- Transaction --> Events
-```
-
-The exact relationship depends on the integration. For example, a merchant can
-split one Sale across multiple payments, while an online purchase commonly
-uses one Checkout to create one successful Transaction.
diff --git a/src/content/docs/tools/glossary/transaction.mdx b/src/content/docs/tools/glossary/transaction.mdx
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----
-title: Transaction
-description: A transaction records the financial outcome of a payment or related operation.
-sidebar:
- order: 50
----
-
-A Transaction is a financial record created when a payment is attempted or a
-related operation is processed. It answers **what happened to the money**.
-
-A Transaction can include:
-
-- The amount and currency
-- Its processing status
-- The payment type and entry mode
-- SumUp and merchant-provided identifiers
-- Card, device, payout, refund, and other event details where applicable
-
-Unlike a [Sale](/tools/glossary/sale/), a Transaction does not describe the full
-basket or commercial context. Unlike a
-[Checkout](/tools/glossary/checkout/), it is not an instruction to collect a
-payment: it records the result of processing one.
-
-## Transaction Lifecycle
-
-```mermaid
-stateDiagram-v2
- [*] --> PENDING: Payment attempt created
- PENDING --> SUCCESSFUL: Payment completes
- PENDING --> FAILED: Payment fails
- PENDING --> CANCELLED: Payment is cancelled
- SUCCESSFUL --> REFUNDED: Full or partial refund
-```
-
-The Transaction status is separate from the Checkout status. For example, a
-Checkout can be `PENDING` while a redirect-based payment is still being
-completed, and its linked Transaction can also have its own `PENDING` state.
-
-## Transactions in the Public APIs
-
-The Transactions API supports the post-payment lifecycle:
-
-- [Retrieve a transaction](/api/transactions/get) by its SumUp ID, transaction
- code, foreign transaction ID, or client transaction ID
-- [List transactions](/api/transactions/list) for a merchant and filter the
- history by status, payment type, entry mode, or transaction type
-- [Refund a transaction](/api/transactions/refund/) in full or partially
-
-Transaction history can include payments, refunds, and chargebacks. A full
-Transaction resource can also contain events related to refunds, chargebacks,
-payouts, and payout deductions.
-
-## Relationship to a Sale and Checkout
-
-A typical online flow starts with a Sale or order in your system. You create a
-Checkout for the amount to collect, then process it. The payment attempt creates
-a Transaction, and the Checkout response links to it through fields such as
-`transaction_id`, `transaction_code`, and `transactions`.
-
-Not every Transaction originates from the online Checkouts API. In-person
-payments initiated through a reader or mobile SDK also produce Transactions.
-Use stable merchant-provided references and store SumUp identifiers so you can
-reconcile each Transaction with the correct Sale.