imutabilidade

In this question I asked about value types and reference types in C#, it was quoted in the accepted answer that instances of ... nged its state. So what does "immutable objects" really mean and how is this concept a useful concept in object orientation?

Researching a bit to better understand the logic that leads strings in Java to be immutable , I found that "Internation" of ... e Flyweight pattern ? When should we use it and what would be good examples of using this technique besides string interning?

Learning Kotlin I came across the following doubt, according to the documentation: Classes in Kotlin can have properties ... ue) } From what I understood from the code Money is a class, I still wanted to understand the use of val in this statement.