> For the complete documentation index, see [llms.txt](https://docs.igenius.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.igenius.ai/fundamentals.md).

# Fundamentals

- [Crystal](https://docs.igenius.ai/fundamentals/crystal.md)
- [Crystal Topics](https://docs.igenius.ai/fundamentals/crystal-topics.md): This page explores the concept of Topics in Crystal.