01
Interaction
HCI studies how people perceive, understand, learn, and use computational interfaces. Interaction design concerns the structure of actions, feedback, state, and system behavior exposed to users.
02
Usability
- Learnability.
- Efficiency.
- Error prevention and recovery.
- Memorability.
- Accessibility.
- User satisfaction.
03
Human-Centered Systems
A technically correct system can still fail if its interface creates cognitive burden, hides important state, or makes consequential actions difficult to understand.