> For the complete documentation index, see [llms.txt](https://docs.substreams.dev/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.substreams.dev/reference-material/core-concepts.md).

# Core Concepts

- [Architecture & Parallel Execution](https://docs.substreams.dev/reference-material/core-concepts/architecture.md): Learn about the Substreams architecture
- [RPC Protocol](https://docs.substreams.dev/reference-material/core-concepts/rpc-protocol.md): Substreams RPC protocol versions and performance optimizations
- [Foundational Stores](https://docs.substreams.dev/reference-material/core-concepts/foundational-store-reference.md): Foundational Store architecture, components, and technical reference
- [Module Concepts](https://docs.substreams.dev/reference-material/core-concepts/modules.md): Learn the basics about modules
- [Module Caching](https://docs.substreams.dev/reference-material/core-concepts/module-caching.md): Learn how Substreams modules are cached for efficient execution
- [Reliability Guarantees](https://docs.substreams.dev/reference-material/core-concepts/reliability-guarantees.md)
- [FAQ](https://docs.substreams.dev/reference-material/core-concepts/faq.md): StreamingFast Substreams frequently asked questions