The term information architecture has been around for many years and is now a term that many people use with ease; however, I'm sure that if you asked ten people their definition of information architecture, you'd get ten different answers. Not wanting to add an eleventh definition, this is simply an overview of what information architecture is about. For a detailed explanation, read the polar bear book—Information Architecture by Rosenfeld and Morville.
In its simplest terms, information architecture is how a site is structured. It is most commonly represented by a site map. There are two main approaches that can be taken in structuring a site—content oriented or task oriented. Although it's not always that simple, more often than not, sites end up a combination of the two.