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

# Fundamentals

> XBOX services fundamentals for GDK developers: identity, sandboxes, Real-Time Activity, XSAPI, game binding, service-to-service auth, and Partner Center config.

Explore fundamentals topics for XBOX game development.

## Subtopics

> **[Game binding](https://docs.xbox.com/services/xbox-services/fundamentals/game-binding/index.md)**
>
> Documentation for game binding.

> **[Identity](https://docs.xbox.com/services/xbox-services/fundamentals/identity/index.md)**
>
> Documentation for identity.

> **[Portal config](https://docs.xbox.com/services/xbox-services/fundamentals/portal-config/index.md)**
>
> Documentation for portal config.

> **[Rta](https://docs.xbox.com/services/xbox-services/fundamentals/rta/index.md)**
>
> Documentation for rta.

> **[S2s auth calls](https://docs.xbox.com/services/xbox-services/fundamentals/s2s-auth-calls/index.md)**
>
> Documentation for s2s auth calls.

> **[Sandboxes](https://docs.xbox.com/services/xbox-services/fundamentals/sandboxes/index.md)**
>
> Documentation for sandboxes.

> **[XBOX services API](https://docs.xbox.com/services/xbox-services/fundamentals/xbox-services-api/index.md)**
>
> Documentation for XBOX services API.

## Guides

> **[XBOX services](https://docs.xbox.com/services/xbox-services/fundamentals/live-xbl-overview.md)**
>
> XBOX services are a collection of micro-services that expose features such as profile, friends and presence, stats, leaderboards,…

## See also

* [Community](https://docs.xbox.com/services/xbox-services/community/index.md)
* [Develop](https://docs.xbox.com/services/xbox-services/develop/index.md)
* [Multiplayer](https://docs.xbox.com/services/xbox-services/multiplayer/index.md)
* [Player data](https://docs.xbox.com/services/xbox-services/player-data/index.md)
* [Storage](https://docs.xbox.com/services/xbox-services/storage/index.md)


## Related topics

- [GameInput fundamentals](https://docs.xbox.com/build/core-features/common/input/overviews/input-fundamentals.md)
- [PlayFab fundamentals](https://docs.xbox.com/services/playfab/get-started/index.md)
- [Gaming Accessibility Fundamentals Learning Path](https://docs.xbox.com/build/game-principles/accessibility/gaf-info.md)
- [Featured Stats overview](https://docs.xbox.com/services/xbox-services/player-data/stats-leaderboards/featured-stats/live-featuredstats-overview.md)
- [PlayFab concepts](https://docs.xbox.com/services/playfab/get-started/concepts.md)