Keywordsとは？

Keyword optimization is the foundation of ASO discoverability. When a user searches "budget tracker" in the App Store, Apple's algorithm scans indexed metadata fields — title, subtitle, and the 100-character keyword field — to determine which apps are most relevant. Google Play also indexes the long description, giving Android developers more keyword real estate.

Effective keyword research involves finding terms with high search volume (many users searching for them) and low difficulty (few competing apps ranking for them). Tools like AppTweak, Sensor Tower, and Mobile Action provide search volume scores and difficulty ratings for app store keywords. Long-tail keywords (three or more words) often offer the best opportunity because they have less competition while still capturing intent-rich searches.

Keyword placement matters as much as keyword selection. The app title carries the most ranking weight, followed by the subtitle, then the keyword field. On iOS, you have exactly 100 characters in the keyword field — use commas to separate terms, never repeat words already in your title or subtitle, use singular forms only (the algorithm handles plurals), and avoid spaces after commas to maximize character usage. Monitor your keyword rankings weekly and iterate based on performance data.