Information architecture is ultimately about establishing and clarifying distinctions; defining sets of things. Grouping items creates a boundary around them: these things are different from those other things in one or more ways. When boundaries are meaningful, people can find (and understand) the items they’re looking for.
Things have different meanings for different people in different contexts. A baseball bat means one thing if you see it alongside a ball in a stadium than if you see it alongside a bloodied glove in a courtroom. We call the first group “equipment” and the latter “evidence.” These labels evoke particular contexts, and thus imbue the items with meaning. If you see a baseball bat in a list titled “evidence,” you know somebody probably got hurt.
That said, a title may not be necessary: sometimes listing the items in the group is enough to convey the context they’re in. Bat, ball, glove, base – the list is enough; I don’t need to place a label above it for you to know what these things mean. (Note I didn’t even have to write “baseball glove”; you got my meaning merely because of the presence of the other items in the list.)
One of the most challenging things about information architecture is that it’s often not clear what groupings (or labelings) will be meaningful to the people who need to use the things we design. Seldom are things as obvious as the baseball example above; you may be called to deal with arcane terminology, novel products, or concepts that are too abstract to relate meaningfully to things people already understand.
To make matters more complicated, the people commissioning the work often have distinctions of their own, groupings that make sense to them. “These products are ‘owned’ by this business unit, ergo they belong together.” If you’re lucky (or if the organization is particularly customer-centric), the groupings may already make sense as an ensemble. In those cases, the work focuses on clarifying labeling. But what if the groupings don’t make sense? Then you must work to establish new groupings and labels. Challenging, especially with organizational gravitational forces pulling towards the established order.
Establishing meaningful distinctions calls for understanding both the context items will be perceived in and the people we intend to make sense of the information. In other words, it calls for research and testing. Creating distinctions people understand requires that you understand them yourself first. When you do, you must then prototype the new order and stress-test (and refine) it with the people it’s intended to serve. Does it make items easier to find and understand? Does it create the right context? Does it make sense to them?