Information Architecture - Structure

Let's ignore fancy colors for a second and play something around UX design, the Information Architecture (IA) design.

Recently, I'm working on designing an IA system for a big healthcare platform. After some literature research, especially after read a book named "Information Architecture: For the Web and Beyond", I tried to visualize four key concepts of Information Architecture design and share them with more people.

#1. Structure: Defines the types of relationships between content items and groups