What is the difference between 'open' and 'public' in Kotlin?

Question

I am new to Kotlin and I am confused between open and public keywords. Could anyone please tell me the difference between those keywords?

Answer 1

All classes, methods, and members are public by default BUT not open

Keyword open in kotlin means "Open for Extension"

means if you want any class to be inherited by any subclass or method to be overriden in subclasses you have to mark as open otherwise you will get compile time error

NOTE: abstract classes or methods are open by default you do not need to add explicitly.