On the internet I see a lot of code which uses this. to access local members of a class, like this:

private String _whatever;
public String Whatever
{
  get
  {
    return this._whatever;
  }
  set
  {
    this._whatever = value;
  }
}

public void DoSomething()
{
  String s = this.Whatever;
  this.DoSomething();
}

(don't expect the code to do something sensible. I just wanted to show a few different uses for "this.")

I wonder why to do this? To add more clarity to the source?
Or is it just a waste of space?