What's New (Release Notes) is the App Store's per-version update text, up to 4,000 characters, and its Google Play counterpart, release notes, capped at 500 characters per language — telling users what changed in each update.
In App Store Connect, What's New in This Version holds up to 4,000 characters, can be localized, and is required for every version after the first. It appears on the product page and in the App Store's list of updates. Guideline 2.3.12 requires apps to describe new features and product changes clearly; a generic description is acceptable only for simple bug fixes, security updates and performance improvements. On Google Play, release notes take up to 500 Unicode characters per language, and Google says not to use them for promotional purposes or to solicit user actions.
What's New isn't among the fields Apple lists for search text relevance — title, subtitle, keywords and primary category — so on the App Store it's a conversion and trust asset rather than a ranking lever. A dated, specific note signals an actively maintained app to a shopper weighing the install, and tells existing users why an update is worth opening. Practitioners list changes in order of importance, credit user feedback where a fix answers a common complaint — both of which Apple recommends — and avoid "bug fixes and improvements" boilerplate on releases that ship real features, since guideline 2.3.12 requires those to be listed.
Example
A budgeting app ships shared budgets and a sync fix. Instead of "Bug fixes and improvements," its What's New opens with "Share a budget with your partner — the feature you asked for most in reviews," then lists the sync fix. Its Google Play release notes carry a shorter version within 500 characters.