Information architecture focuses on the broad idea about how information should be organized. The information architect, instructional designer, web developer, or technical writer evaluates the content or subject and develops a logical pattern of categories.
For example, an instructional designer takes a list of objectives and organizes those in a way to present a learning strategy to their audience. That strategy may be in the form a multi-course curriculum with each course focusing on a specific topic. Another IA practice is structuring subjects or audience type in a Learning Management System (CMS), so that course material can be assigned or searched based upon a subject or job title.
The technical writer evaluates a software tool or mechanical device and identifies what deliverables (manuals or online help system) best assists the user. Those deliverables are broken down into sections where users can search, locate, and consume content.
In the case of web sites, information architecture is presented to a visitor in the navigation and menus. The navigation is closely related to how that linked information is structured in the CMS.
Large banks of content, like you see on this website, are structured in a CMS. Articles and blogs are stored inside categories. These categories create an organized structure for the content. This same structure is presented, visually, to visitors through the site navigation and menus. Organized navigation and menus enable visitors to locate a specific article or related content among the hundreds that reside in the database. Think of all the problems that would befall a web developer, or site visitor, if no organized method of storing content were established.
Organizing content in the early stages of a project may seem like a distraction from the development or deployment tasks, but content is king and the reason for the project to begin with. Information architecture helps identify the requirements of the project and in many cases the technology. So for your next project, invest time in structuring the content before you execute development and realize the great dividends that result from this effort.