Newbie question - "no property of label2 found in the interface"

Question

In the HelloWorld sample application, I added a second label.
Then, in MyController.h, inside "@interface MyViewController", where label was defined as
IBOutlet UILabel *label;
I added a line below that
IBOutlet UILabel *label2;
After doing that, in the Interface Builder, I was able to connect a line from the label to File's Owner and "label2" appeared amongst the selection there, so I made the connection. I figure I did that right.
As far as that goes, the app built and ran ok with no errors.
In MyViewController.m, however, I noticed there was a line:
@synthesize label;
I still don't understand what that means, but figured if there was one for label I ought to add one for label2 as well, so I added a 2nd line
@synthesize label2;
However, if I do that, I get a compile-time error: "no declaration of property "label2" found in the interface.
My questions are:
(1) Why do I get that error if I did, in fact, declare label2 in the interface?
(2) What does @synthesize mean anyway?
Thanks,
doug

Answer 1

Thanks, g.difalco.
Yes, that what was missing. When I added
@property (nonatomic,retain)UILabel *label2;
the compile error went away even with the @synthesize label2 in the MyViewController.m file. Thanks. While looking for "symmetry" with the label definition on the MyViewController.h file I overlooked that one.
Now let's see if I can wrap my mind around the rest of what you said. I am new to Objective-C, but I did read that the "dot syntax" for properties that I have been used to for years in JavaScript is a relatively recent addition to the language.
So you are saying that the @synthesize line allows that new, convenient syntax to be used.
OK. I'll go along with that. I don't know why the word "synthesize" is use for that purpose, but I will let that sink in.
Is there a reason the @synthesize line goes in the @implementation inside MyController.m rather than in the @interface in MyController.h?
Thanks,
doug