Explain whats going on with Deployment.CurrentDispatcher.BeginInvoke(() => ........

Question

I am updating a text box on an xmal page. I was getting an issue "UnauthorizedAccessException when trying to update the UI.

A bit of searching and I found the solution was as follows:

 
Deployment.Current.Dispatcher.BeginInvoke(() =>
{
this.ResponseText.Text = "Using HttpWebRequest: " + resultString;
}
);

Its cool that my issue is resolved, but i need to understand whts going on above. I dont understand the syntax "() >={//code} . Can anyone break this down, for an absolute novice?