A preprint posted on arXiv offers a clear introduction to quantum correlations in prepare-and-measure scenarios, explaining how quantum systems can provide advantages over classical methods in communication and information tasks. This is a review paper, not an experimental study, so it includes no original methodology, sample sizes, or new empirical data; instead it summarizes recent theoretical developments and notes proof-of-principle demonstrations already reported for quantum randomness certification and key distribution. The authors highlight semi-device-independent approaches that balance security, performance, and ease of implementation, while stressing these ideas are still in the exploratory stage. You can read the full paper at https://arxiv.org/abs/2603.23604. As a preprint, it has not yet undergone peer review.