Information Architecture (IA) is the structural design of shared information environments; the art and science of organizing and labeling websites, intranets, online communities and software to support usability and findability. It involves creating site maps, hierarchies, categorizations, and navigation schemes.
Poor IA leads to user frustration and abandonment. If users cannot find what they are looking for, the feature doesn't exist to them. Scalable IA is critical for long-term product growth, preventing the interface from becoming a cluttered mess as new features are added.
Structure precedes surface. We do not design screens until we have designed the system. Our IA is object-oriented (OOUX), focusing on the core entities of the domain and their relationships, rather than just transient pages.