What do two question marks together mean in C#?

Question

Ran across this line of code:

FormsAuth = formsAuth ?? new FormsAuthenticationWrapper();

What do the two question marks mean, is it some ki

Answer 1

Thanks everybody, here is the most succinct explanation I found on the MSDN site:

// y = x, unless x is null, in which case y = -1.
int y = x ?? -1;