Single Blind Review
The names of the reviewers are hidden from the author. This is the traditional method of reviewing and is, by far, the most common type of peer review.
Reviewer anonymity allows for impartial decisions free from influence by the author.
Authors fear the risk that reviewers working in the same field may withhold submission of the review in order to delay publication, thereby giving the reviewer the opportunity to publish first.
Reviewers may use their anonymity as justification for being unnecessarily critical or harsh when commenting on the author’s work.