Difference between Optional and Implicitly Unwrapped Optional | Important Swift Interview Question!

This looks pretty straightforward but this normal variable question can create a hell lot of confusion during the interview. Q: Can you set nil to a! Q: If we set nil to a! then how would you decide between a! and a? Q: How would you decide between a and a! Q: Why storyboard outlets are Implicitly Unwrapped Optional? Please let us know your feedback. Thanks you!