Distinguishability is how easily visually similar characters can be told apart. In data visualization, it matters especially for small axis labels, data labels, annotations, and captions, where letter shape becomes part of readability. section 5.2.1
Use distinguishability as a practical check when choosing fonts for compact visualizations:
- Prefer a regular weight for most small text; very thin and very heavy weights can lose the balance between ink and white space. section 5.2.1
- Reserve extreme weights for larger titles or headers, or use heavier weight sparingly for emphasis. section 5.2.1
