* [Druid: A Real-time Analytical Data Store](http://static.druid.io/docs/druid.pdf) - Discusses the Druid architecture in detail.
* [The RADStack: Open Source Lambda Architecture for Interactive Analytics](http://static.druid.io/docs/radstack.pdf) - Discusses how Druid supports real-time and batch workflows.
* [Introduction to Druid](https://www.youtube.com/watch?v=hgmxVPx4vVw) - Discusses the motivations behind Druid and the architecture of the system.
* [Druid: Interactive Queries Meet Real-Time Data](https://www.youtube.com/watch?v=Dlqj34l2upk) - Discusses how real-time ingestion in Druid works and use cases at Netflix.
* [Not Exactly! Fast Queries via Approximation Algorithms](https://www.youtube.com/watch?v=Hpd3f_MLdXo) - Discusses how approximate algorithms work in Druid.
* [Stories from the Trenches - The Challenges of Building an Analytics Stack](https://www.youtube.com/watch?v=yuSLeIzG98w&t=55s) - Discusses features that were added to scale Druid.