> For the complete documentation index, see [llms.txt](https://resources.atriptech.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://resources.atriptech.com/api-document/support-and-reference/atlas-api-concepts.md).

# Atlas API concepts

Definitions of Atlas API booking flows, identifiers, order lifecycle terms, and integration concepts.

This glossary defines the terms used across Atlas API documentation.

Use it to interpret workflow guides, endpoint references, and error guidance consistently.

### What is Atlas API?

Atlas API supports flight shopping, booking, payment, ticketing, and post-booking operations.

Start with [What is Atlas API?](/api-document/what-is-atlas-api.md) for product capabilities and documentation entry points.

### Booking flows

#### Standard booking

The standard path starts with `search.do`.

It uses `routingIdentifier` for `verify.do`, then `sessionId` for `order.do`.

See [Standard booking](/api-document/product-guides/booking/booking-flows/standard-booking-flow.md).

#### Get Offer

Get Offer prices a known itinerary with `getOffers.do`.

It returns an `OfferId` used for order creation.

See [Get Offer](/api-document/product-guides/booking/booking-flows/get-offer-flow.md).

#### Fulfilment API

Fulfilment API uses `getOfferPrice.do` to price an offer.

Its flow uses a short-lived `OfferId` and fast payment after order creation.

See [Fulfilment API](/api-document/product-guides/booking/booking-flows/fulfillment-flow.md).

### Core identifiers

#### `routingIdentifier`

`search.do` returns this route token.

Pass it to `verify.do` in the standard booking flow.

#### `sessionId`

`verify.do` returns this booking context.

Pass it to `order.do` in the standard booking flow.

#### `OfferId`

`getOffers.do` or `getOfferPrice.do` returns this offer context.

Use it for `order.do` in its matching booking flow.

#### `orderNo`

`order.do` returns the Atlas order identifier.

Use it for payment, order queries, ticketing follow-up, and post-booking actions.

See [Identifiers](/api-document/product-guides/booking/booking-overview/identifiers.md) for validity periods, flow mapping, and refresh rules.

### Order lifecycle

An order is created with `order.do`.

Payment and ticketing start through `pay.do` where the flow requires it. Use `queryOrderDetails.do` to check order status and ticketing progress.

See [Payment & Ticketing](/api-document/product-guides/booking/booking-step-guides/payment-and-ticketing.md) and [Query Order](/api-document/product-guides/booking/booking-step-guides/query-order.md).

### Webhooks and incidents

A webhook delivers Atlas event notifications to your endpoint.

Use webhooks for ticketing, void, schedule-change, airline-status, email, and incident notifications.

See [Webhook Overview](/api-document/product-guides/extensions-and-integrations/webhook-overview.md).

### Related documentation

* [Product Guides](/api-document/product-guides.md)
* [API Reference](/api-document/api-reference.md)
* [Atlas API FAQs](/api-document/support-and-reference/troubleshooting-and-support/faqs.md)