If this is "off-topic", please ignore:
What exactly is an "identity card" and how does it work? Here in the U.S., we have driver's licenses and social security cards which we may use to prove our identity from time to time. But is your identity card something that you are required to carry with you at all times and can be asked to produce by the authorities at any time? If so, what would happen if you didn't have it on you?