---
title: "Foundations"
description: "Core concepts and infrastructure that every SDK builds on - transport protocol, data model, contexts, scopes, and attributes."
url: https://develop.sentry.dev/sdk/foundations/
---

# Foundations

The building blocks every SDK depends on. Understand how SDKs communicate with Sentry and the data structures they share.

* #### [Client](https://develop.sentry.dev/sdk/foundations/client.md)

  The SDK component responsible for event creation, integration management, and transport dispatch.

* #### [State Management](https://develop.sentry.dev/sdk/foundations/state-management.md)

  How SDKs manage contextual state — scopes, attributes, breadcrumbs, and the deprecated Hub model.

* #### [Trace Propagation](https://develop.sentry.dev/sdk/foundations/trace-propagation.md)

  How SDKs propagate trace context between services via headers, metadata, and environment variables.

* #### [Data Scrubbing](https://develop.sentry.dev/sdk/foundations/data-scrubbing.md)

* #### [Processing](https://develop.sentry.dev/sdk/foundations/processing.md)

  How SDKs buffer, prioritize, and forward telemetry data to the transport layer.

* #### [Transport](https://develop.sentry.dev/sdk/foundations/transport.md)

  How SDKs send data to Sentry - envelope format, authentication, compression, and rate limiting.

## Pages in this section

- [Client](https://develop.sentry.dev/sdk/foundations/client.md)
- [State Management](https://develop.sentry.dev/sdk/foundations/state-management.md)
- [Trace Propagation](https://develop.sentry.dev/sdk/foundations/trace-propagation.md)
- [Data Scrubbing](https://develop.sentry.dev/sdk/foundations/data-scrubbing.md)
- [Processing](https://develop.sentry.dev/sdk/foundations/processing.md)
- [Transport](https://develop.sentry.dev/sdk/foundations/transport.md)