Explore the concept of Reactive Systems as a modern architectural approach for 21st-century software development in this 55-minute conference talk from GOTO Copenhagen 2015. Delve into the changing landscape of software design, examining how conventional assumptions no longer meet current demands. Learn about the Reactive Manifesto and the key properties of Reactive Systems, including their fractal architecture. Investigate the challenges of synchronous messaging and discover the benefits of asynchrony. Gain insights into important concepts such as idempotence, isolation, back-pressure, eventual consistency, and location transparency. Understand how modern hardware should influence architectural decisions and explore the implications of Conway's Law and Bounded Contexts. Examine a practical example of a Reactive, Microservice architecture and receive guidance on where to begin implementing these principles in your own projects.