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The Kotlin stdlib ships with the language itself, so its core types behave the same on Android, iOS, desktop and beyond.

The String type is fully multiplatform. You can declare and combine text in commonMain and trust it everywhere.

Handy String functions like uppercase, trim and length all live in common code, ready on each platform.

Number types such as Int, Long and Double are part of common Kotlin, so your math is identical across targets.

Conversions like toInt and toDouble are common-safe, letting you reshape numbers anywhere your shared code runs.

A List holds an ordered group of items. It is multiplatform, so the same collection powers both apps.

A Set stores each value only once. Like List, it works the same way on every Kotlin target.

A Map links keys to values. It is fully shared, so lookups behave identically across all platforms.

Use indexing or getOrNull to read from a list. These collection operations are common-safe across targets.

Because these core types are identical everywhere, you write data logic once and never worry which platform runs it. 🙂

Reach for plain String, Int, List, Set and Map first. They are the safe, portable backbone of shared Kotlin.

Core stdlib types, String, numbers, List, Set and Map, behave the same on every target, so shared data logic is rock solid.