Apache OpenWhisk is an open-source, state-of-the-art, serverless computing platform. It was developed by my group at the IBM T.J. Watson Research Center. It now powers IBM Cloud Functions and the Adobe I/O Runtime. It is also integrated with Red Hat’s OpenShift and deployed on-prem in several organizations worldwide. In the serverless model, you can easily stand up rich backend solutions without explicitly provisioning virtual machines, containers, or middleware. The system automatically provisions resources based on the offered load and bills based on actual usage at a sub-second granularity. OpenWhisk provides a rich, event-based, programming model with which you can integrate and compose backend actions with simple declarative tools. This talk will describe the OpenWhisk architecture and explain how we leverage container technology to isolate functions while still churning through millions of containers and delivering low latency and scale. I will also describe how functions – the building blocks of serverless – are only the beginning of a larger disruptive trend in programming for the cloud. I will share some of our latest work on composition of functions to build application, and the challenges one faces in the serverless cloud.