### Nielsen's 10 Usability Heuristics

1. **Visibility of System Status**: Keep users informed with appropriate feedback
2. **Match Between System and Real World**: Use familiar language and concepts
3. **User Control and Freedom**: Provide undo, redo, and easy exits
4. **Consistency and Standards**: Follow platform conventions
5. **Error Prevention**: Design to prevent errors before they occur
6. **Recognition Rather Than Recall**: Make options and actions visible
7. **Flexibility and Efficiency of Use**: Accelerators for expert users
8. **Aesthetic and Minimalist Design**: Remove irrelevant information
9. **Help Users Recognize, Diagnose, and Recover from Errors**: Clear error messages
10. **Help and Documentation**: Provide searchable, task-focused help

### Cognitive Load

**What Is It?**
The mental effort required to use an interface. High cognitive load leads to user frustration and errors.

**Reducing Cognitive Load:**
- Chunk information into digestible pieces
- Use progressive disclosure
- Provide clear visual hierarchy
- Minimize choices (paradox of choice)
- Use familiar patterns and conventions
- Reduce required memory with visual cues

### Fitts's Law

**What Is It?**
The time to reach a target is proportional to distance and inversely proportional to target size.

**UI Implications:**
- Make important buttons large and easy to reach
- Place frequently used actions in accessible areas
- Increase touch targets for mobile (minimum 44x44px)
- Use edge and corner positions for key actions (infinite depth)

### Hick's Law

**What Is It?**
Decision time increases logarithmically with the number of choices.

**UI Implications:**
- Limit options to reduce decision time
- Categorize and group related options
- Use progressive disclosure for complex choices
- Highlight recommended options

### Gestalt Principles

- **Proximity**: Elements close together are perceived as grouped
- **Similarity**: Similar elements are perceived as related
- **Closure**: Mind completes incomplete shapes
- **Continuity**: Eyes follow continuous lines and patterns
- **Figure-Ground**: Perception of foreground and background
- **Common Fate**: Elements moving together are perceived as grouped

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