Textbook of Usability

Also known as: IA

Information architecture (IA) is the organisation, labelling, and structuring of content so that users can find what they need. The field was named by Richard Saul Wurman and developed by Peter Morville and Lou Rosenfeld in Information Architecture for the World Wide Web (1998). Good IA is invisible to users; bad IA generates constant navigation failures.

Common IA patterns:

• Hierarchical (tree structure) — categories and subcategories. Works when categories are intuitive and mutually exclusive.
• Flat (hub and spoke) — a central page links directly to all content. Works for small collections.
• Faceted — content filtered along multiple independent dimensions (price, colour, size). Works for large heterogeneous collections.
• Search-dominant — search bar as primary navigation. Works when users know what they want.

The organisation of content should be based on how users think, not how the organisation is structured internally. Methods for validating IA with users include:

• Card sorting — participants group content items into categories
• Tree testing — participants find items in a proposed hierarchy
• First-click testing — where do users click first when trying to complete a task?

Well-designed navigation answers three persistent questions in the user's mind:

1. Where am I? (breadcrumbs, highlighted menu item)
2. Where can I go? (visible navigation options)
3. How do I get there? (labelled links and buttons)

Information architecture sits at the intersection of library science, cognitive psychology, and user research.