# 

Background, not instructions. You can integrate successfully without reading it,
but the vocabulary here turns up in responses and support conversations.

## The parties

```mermaid
---
config:
  theme: 'neutral'
---
flowchart LR
    A[Cardholder] --> B[Your application]
    B --> C[Gateway]
    C --> D[Processor]
    D --> E[Card network]
    E --> F[Issuing bank]
    F --> E --> D --> C --> B
```

| Party | Does |
|  --- | --- |
| Cardholder | Presents a card |
| Merchant | Sells the thing. Your customer, or you |
| **Gateway** | Takes an API request and turns it into a processor message. This is us |
| Processor | Connects to the card networks. TSYS, for cards |
| Card network | Visa, Mastercard, Amex, Discover. Routes to the issuer |
| Issuing bank | Holds the cardholder's account and decides approve or decline |
| Acquiring bank | Holds the merchant's account and receives the funds |


**You talk to the gateway and nothing else.** No direct connection to a
processor, a network, or a bank is needed.

## Authorization, then settlement

A card payment is two events, usually hours apart.

**Authorization** asks the issuer to reserve funds. It is synchronous — the
answer comes back in the API response, and it is where an approval or a decline
happens.

**Settlement** actually moves the money. Transactions gather in a batch, the batch
closes on a schedule, and the acquirer funds the merchant a day or two later.

That gap is why `is_settled` is `false` on a transaction you just approved, and
why a void and a refund are different operations. See
[Transaction lifecycle](/docs/after-the-payment/transaction-lifecycle).

## What the gateway does for you

|  |  |
|  --- | --- |
| One integration | Card and ACH through one API, rather than one per processor |
| Tokenization | A [payment token](/docs/payments/save-and-reuse-a-payment-method) instead of storing card numbers |
| Normalized responses | The same transaction object whichever processor handled it |
| Settlement | Batching and close, with [reporting](/docs/after-the-payment/batch-reports) to reconcile against |


## Next steps

* [Card networks and interchange](/docs/concepts/card-networks-and-interchange)
* [Transaction lifecycle](/docs/after-the-payment/transaction-lifecycle)
* [Accept a card payment](/docs/payments/accept-a-card-payment)