The process of peer review does not end after a paper completes the peer review process. After being put to press, and after 'the ink is dry', the process of peer review continues as publications are read. Readers will often send letters to the editor of a journal, or correspond with the editor via an on-line journal club. In this way, all 'peers' may offer review and critique of published literature. A variation on this theme is open peer commentary; journals using this process solicit and publish non-anonymous commentaries on the "target paper" together with the paper, and with original authors' reply as a matter of course. The introduction of the "epub ahead of print" practice in many journals has made possible the simultaneous publication of unsolicited letters to the editor together with the original paper in the print issue.