Unconditionally secure communication means that even an infinitely powerful adversary cannot break the confidentiality nor the authenticity of the system. Classical results by Shannon dating back some 50 years seem to imply that unconditionally secure solutions are doomed to being impractical, if not impossible. However, in recent years, new research has shown that these results were based on rather pessimistic assumptions on the amount of information available to an adversary. It turns out that in many practical scenarios, these assumptions are not satisfied, e.g., when communication is noisy, in large networks where not all nodes can be hacked into, or when quantum communication is used. In all these settings, unconditional particular emphasis on quantum communication.