> For the complete documentation index, see [llms.txt](https://docs.finngen.fi/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.finngen.fi/working-in-the-sandbox/which-tools-are-available/atlas.md).

# Atlas

Atlas is a cohort building tool from the Observational Health Data Sciences and Informatics [(OHDSI) program](https://www.ohdsi.org/).

See the [Quick guide](/working-in-the-sandbox/which-tools-are-available/atlas/quick-guide.md) for getting started with Atlas and building your first cohorts.

See the [Detailed guide](/working-in-the-sandbox/which-tools-are-available/atlas/detailed-guide.md) for more information and more features of the Atlas tool.