Defining a Contructor wih a ~ (tilde)

Hi there:

I'm checking some article and I ran into this:

  public partial class MyClass {
     public MyClass(string something) {
     // Some stuff
     }

     ~MyClass() { // HERE: I know that this is the default constructor, but, what is "~" ?
     // Some other stuff... 
     }
  }

Thanks in advance for your answer.

Raael