title: What are the advantages of built-in immutability of F# over C#?
body: <ol>
  <li><p>I heard F# has native support for immutability but what about it that can not be replicated in C#? What do you get by an F# immutable data that you don't get from a C# immutable data?</p></li>
  <li><p>Also in F#, is there no way to create mutable data? Is everything immutable?</p></li>
  <li><p>If you use both C# and F# in an application, can you change the immutable F# data in C#? Or do you just have to create new C# types that uses the immutable F# data and replaces the references that points to those data?</p></li>
  </ol>