Design of Everyday Things Framework
Foundational design principles for creating products that are intuitive, discoverable, and understandable. The "bible of UX" — applicable to physical products, software, and any human-designed system.
Core Principle
Good design is actually a lot harder to notice than poor design, in part because good designs fit our needs so well that the design is invisible. When something works well, we take it for granted. When it fails, we blame ourselves — but the fault is almost always in the design.
The foundation: Design must bridge the gap between what people want to do and what the product allows them to do. The best designs are discoverable (users figure out what to do) and understandable (users figure out what happened).
Scoring
Goal: 10/10. When reviewing or creating designs, rate 0-10 based on discoverability, understandability, and error prevention. A 10/10 means users can figure out what to do without instructions, understand what happened, and recover from errors easily. Always provide current score and improvements to reach 10/10.
The Two Gulfs
Every interaction with a product requires bridging two gulfs:
USER PRODUCT
│ │
├──── Gulf of Execution ────────────────→│
│ "How do I do what I want?" │
│ │
│←──── Gulf of Evaluation ──────────────┤
│ "What happened? Did it work?" │
Gulf of Execution
The gap between what users want to do and what the product lets them do.
Questions users ask:
- What can I do here?
- How do I do it?
- Which control do I use?
- How do I operate this control?
Bridging strategies:
- Clear signifiers showing what's possible
- Natural mappings between controls and outcomes
- Constraints preventing wrong actions
- Familiar conceptual models
Gulf of Evaluation
The gap between what the product did and what users understand happened.
Questions users ask:
- What happened?
- Did it work?
- Is this what I wanted?
- What state is the system in now?
Bridging strategies:
- Immediate, visible feedback
- Clear system state indicators
- Meaningful error messages
- Progress indicators
Design goal: Make both gulfs as narrow as possible. The ideal design requires zero bridging — action and understanding are immediate.
See: references/two-gulfs.md for gulf analysis exercises.
Seven Fundamental Design Principles
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