Peer-review is the system used to assess the quality of a manuscript before it is published. Independent researchers in the relevant research area assess submitted manuscripts for originality, validity and significance to help editors determine whether the manuscript should be published in their journal. You can read more about the peer-review process here.
Harm Reduction Journal operates a single-blind peer-review system, where the reviewers are aware of the names and affiliations of the authors, but the reviewer reports provided to authors are anonymous.
The benefit of single-blind peer review is that it is the traditional model of peer review that many reviewers are comfortable with, and it facilitates a dispassionate critique of a manuscript.