The document discusses serverless patterns and design. It begins with an overview of serverless computing and examples of how serverless architectures can be used to build web/mobile backends, extend existing applications, process streams/files in real-time, connect IoT devices, run batch jobs, and automate DevOps tasks. It then covers serverless concepts like events, execution models, and error handling. The document emphasizes that serverless applications should be broken into small, single-purpose functions and that functions should be separated and simplified for observability.