C# Automatic Properties - Why Do I Have To Write "get; set;"?

Question

If both get and set are compulsory in C# automatic properties, why do I have to bother specifying "get; set;" at all?

Answer 1

Because you might want a read-only property:

public int Foo { get; private set; } 

Or Write-only property:

public int Foo { private get; set; }