The iOS Developer's Guide To Apple App Store Categories

While app categorization is not the most critical factor for ASO success compared to keywords, icons, localization, or screenshots, it still offers advantages.
Some apps have obvious categories, but others have options.
Apple reviews chosen categories for relevance, so avoid mismatch.
Always select a secondary category to maximize exposure.
If multiple categories fit, use leaderboards to assess competition; a less competitive category improves ranking chances.
For example, a surf weather app might choose Weather over Travel due to lower competition metrics.
However, relevance should prevail.
The article provides a GitHub Gist with category definitions for easy reference.
Ultimately, testing and tracking ASO changes is essential to measure impact on downloads.