Everyone's talking about AI powered apps. Almost nobody explains what's actually happening inside one. Let me fix that. Most people experience AI powered apps as a black box. You type something in, something useful comes out, and whatever happened in between feels like magic. It isn't magic. It's a repeatable structure.. and once you understand it, you start seeing how it applies to almost any business problem. Here's what's actually happening inside every AI powered app: Layer 1 - The Input Something triggers the system. A user types a message. A form gets submitted. A document gets uploaded. A scheduled task fires automatically. This is the entry point, whatever the user or system sends in to start the process. Layer 2 - The System Prompt This is the invisible layer most people never see.. and the most important one. Before the AI ever reads the user's input, it receives a set of instructions that defines everything about how it should behave. Its role, its tone, what it knows, what it's allowed to do, what it should never do. This is where the intelligence gets shaped. A vague system prompt produces a generic output. A precise one produces something that feels like it was built specifically for that business. Layer 3 - The Model This is Claude, or whichever model is doing the reasoning. It takes the system prompt and the user input together, reasons through them, and produces a response. The model choice matters: more complex tasks need more powerful models. Simpler, high-volume tasks can use faster, cheaper ones. Matching the model to the task is part of the craft. Thread