In single anonymized peer review, the author does not know the reviewer's identity, but the reviewer does know the author's identity.
In double anonymized peer review, the author and reviewer are both ignorant of the other's identity.
These have traditionally been called single blind and double blind peer review, and those terms will still be encountered, though many are moving away from the ableism of the term "blind."
Some platforms support peer review commentary on research after it is published, which can help to facilitate discussion about the quality, methodology, and findings of research.
As Bonnie Swoger writes on Scientific American's Information Culture blog, "In the early days of scientific societies (i.e. the 17th century), scientists would share their experimental results with each other at meetings, and receive feedback about their experiments in person. (The scientific journal wasn’t invented until later.) As the scientific community grew, it was impossible for everyone to be in the same room to hear about results, and so the amount of immediate feedback offered was limited to a few conferences or other gatherings. Recently, publishers, scientific societies and entrepreneurs have begun using the web to bring back the era of immediate feedback: so-called 'post-publication peer review.'"
Open Peer Review (OPR) is an evolving approach to the review of scholarly publications. Unlike blind and double-blind review systems, OPR makes both the author and reviewer identities known. This may be done during review or after an article is published; the specific implementation of OPR varies among journals, with some even providing platforms for non-referee public commentary on a published article.
"Signed review" is a related term sometimes used when the reviewer is identified.
Supporters believe this transparency may help to improve reviewer accountability, decrease editorial and reviewer bias, and increase speed of review. The approach of developmental peer review additionally treats open review as a way to help less experienced authors develop their skills in open dialog with reviewers.
Being identified may also help reviewers to receive more visibility for this professional service, especially with the rise of various tools for verifying and crediting reviewer activity.
F1000 Research, an open publishing platform in the life sciences, is just one example of OPR in action.
Be aware of OPR as an author, as well as when you may take on the reviewer's role--If you are given the choice of participating in this review model, you should know the potential benefits or risks that it may pose for you and your work.
Should a reviewer's anonymous comments be published with an article as part of the scientific record? Some say yes.