What's an immutable architecture, and why do you want one? Carl and Richard talk to Michael Perry about his book The Art of Immutable Architecture and the power of historical models. Michael talks about different designs for immutability, the ability to always look back through data, to avoid conflict between resources, and the advantages of eventual consistency. As Michael says, you already use immutable architecture - look at Git and how you only add new files to the system, always able to get back to a previous state! The conversation dives into implementing architecture in a way that helps to show where immutability makes sense.