Explore the principles of Reactive Systems in this 54-minute conference talk from GOTO Copenhagen 2019. Discover how modern software architectures can address 21st-century challenges, including distributed systems, high data throughput, and 24/7 service expectations. Learn about the Reactive Manifesto and its key properties: Responsive, Resilient, Elastic, and Message Driven. Delve into topics such as fractal architecture, synchronous messaging pitfalls, services as state machines, idempotence, message-based persistence, back-pressure, location transparency, and linear scalability through sharding. Gain insights on implementing reactive microservice architectures and find practical starting points for adopting these principles in your own projects.