Before adventurers can explore the world, they must understand the rules that shape it. Editor’s Note Before appearing as the opening chapter of The Full-Stack Campaign: From Interface to Infrastructure, this article first appeared on RandomThoughtsInTraffic.com as an exploration of why developers often struggle when their knowledge remains confined to a single layer of the technology stack. This revised and expanded edition examines how information travels through modern web applications, explores the relationships between browsers, APIs, servers, databases, and infrastructure, and establishes the systems-oriented mindset that guides the remainder of the series. New material includes expanded architectural examples, a deeper discussion of specialization within software development, and a practical examination…