NNGroup Information Architecture IA (Three IA Models · IA vs Sitemap · Flat vs Deep Hierarchies · Full Taxonomy Workflow · Left-Side Vertical Navigation · 5 Common Pitfalls of Privacy Policy Pages)
6 essential articles from the Nielsen Norman Group Information Architecture (IA) knowledge base. It starts with a clear definition of IA: IA is the practice of organizing, categorizing, and labeling content and designing relationships between content (it is not a single deliverable, but an ongoing optimization process). There are three core axes: ① The three models of IA — Visible Navigation (Front Stage, including menus/links/breadcrumbs/accordions, aligned with users' mental models) / Underlying IA Structure (Back Stage, the blueprint of full-site page relationships ≈ Sitemap) / Taxonomies & Metadata (concept relationship maps that organize 'concepts' rather than 'content', more technical); it also clarifies IA vs sitemap (IA is the overall practice including Content Inventory, Content Audit, IA UX research such as Card Sorting/Tree Testing, and taxonomy labels, while a sitemap is only its visual output, with nngroup.com as an example using 3 levels of blue/green/yellow nodes). ② Structural choices — Flat vs Deep Hierarchies: flat structures offer strong visibility and low interaction cost but cause information overload; deep structures keep the top level concise but increase cognitive load and lengthen click paths; examples include the New Zealand government's flat structure with 15 top-level categories vs Ernst & Young's deep structure with 5 top-level categories (11 subcategories under Services, 10 further subdivisions under Consulting); the conclusion is to avoid extremes, moderately flat structures outperform moderately deep structures, and user research is key. ③ Navigation and content page implementation — Left-Side Vertical Navigation (accommodates multiple categories, is extensible, easy to scan, users devote 80% of their attention to the left half of the screen; Abel Restaurant uses 13 categories, Slack/Gmail also use it; counterexamples include Accenture hiding everything under a single 'Services' item, Nua Bicycles with a content-to-chrome ratio changing from 5:1 to 12:1; 5 best practices: prominent left alignment / no duplicate navigation / icons paired with text / long menu optimization / mobile adaptation); full Taxonomy workflow (Controlled Vocabulary, hierarchical, non-extensible, supports Faceted Navigation as used by the US Library of Congress and search suggestions as used by the World Bank; compared with Thesaurus and Ontology, 8-step construction method at BARTOC.org); 5 common mistakes on privacy policy/terms of service pages (obscure language, lack of overview, poor typography with font size below 14pt, incomplete navigation, placement not matching user expectations; positive examples include LinkedIn/eBay/Google, counterexamples include Forever21/Ameren/Spotify using all caps). Target audience: product managers, with in-line explanations of jargon, decision-oriented (when to use/how to choose/counterexamples).