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# Introduction

52ViKING is FiftyTwo's retail platform. It runs the point of sale: the staffed
till, the mobile POS a shop assistant carries, the self-checkout, the emergency
POS that keeps a store trading when the network drops. It also holds the rules
that decide what a customer pays.

The APIs documented here give an external system access to that same engine.

#### [Master Data](/api/master-data/overview)

Write the catalogue: articles, groups, campaigns, discount groups, coupons,
customers, operators, store groups.

#### [Basket](/api/basket/overview)

Ask what a basket costs and get the answer a till would give.

#### [Transaction POS Log](/api/transactions/overview)

Receive transaction events as they happen.

#### [Register Sale](/api/register-sale/overview)

Push finished external sales into ViKING POS.

#### [Order](/api/order/overview)

Order requests for click & collect and ship-from-store.

#### [Auth](/api/auth/overview)

Get the access token every other call needs.

## How the pieces fit

The platform splits into two halves, and knowing which half you are talking to
explains most of the API design.

**The store** runs ViKING locally. Tills, the store server, and the peripherals
are on-premise (or in a hybrid cloud) so that a shop keeps selling when its
connection to the outside world does not. Discount evaluation, receipt
printing, and till balancing all happen here.

**52 Cloud** sits in front of the estate. It takes master data in, distributes
it to stores through the enterprise controller, and streams transaction data
back out. This is what the APIs on this site talk to.

> **Note**
>
> Because stores are authoritative for their own trading, most writes are
> **asynchronous**. Master Data returns `202 Accepted` with a location you poll;
> Register Sale returns a correlation ID you poll. Design for that from the
> start. See [Errors and retries](/docs/errors).

For the full architectural picture, see
[Understand ViKING architecture](/help/store-management/arch).

## Which API do I need?

| I want to…                                        | Use                                               |
| ------------------------------------------------- | ------------------------------------------------- |
| Load or update products, prices, and promotions   | [Master Data](/api/master-data/overview)          |
| Show a correct online price, including promotions | [Basket](/api/basket/overview)                    |
| Let a customer return a webshop order in a store  | [Register Sale](/api/register-sale/overview)      |
| Get receipts and end-of-day data out of the POS   | [Transaction POS Log](/api/transactions/overview) |
| Build click & collect                             | [Order](/api/order/overview)                      |
| Authenticate any of the above                     | [Auth](/api/auth/overview)                        |

## Vocabulary

52ViKING's domain language is specific, and the API field names use it directly.
A few terms that trip people up:

* An **article** is a sellable product. Articles belong to **article groups**
  (hierarchy) and **discount families** (promotion grouping).
* A **discount group** is a promotion rule. Its **Buy side** lists the articles
  that trigger the discount; its **Get side** lists the articles that receive
  it.
* An **operator** is a person who can sign into a till. A **salesperson** is who
  gets credited with the sale. They are often, but not always, the same human.
* A **till** is one POS. **Bpar** is the store configuration utility your
  FiftyTwo consultant manages.

The [Glossary](/docs/glossary) has the full list, and every term links to the
help-center topic that explains it properly.

## Next

#### [Authentication](/docs/authentication)

Get a token.

#### [Your first API call](/docs/first-call)

Price a basket in about five minutes.

#### [Integration guides](/docs/guides/sync-catalog)

The four things teams usually build.