COPE has produced guidelines that set out the basic principles and standards to which all peer reviewers should adhere, which we reproduce below. We recommend reading the full document at https://publicationethics.org/resources/guidelines-new/cope-ethical-guidelines-peer-reviewers. Thus, during the peer review process, reviewers should: 

• Agree to only review manuscripts whose subject matter is within their domain, so that they can perform an appropriate and timely evaluation. 
• Not to use information obtained during the peer review process for your own benefit or that of another person or organization, or to harm or discredit others. 
• Respect the confidentiality of peer review and not reveal any details of a manuscript or its review, during or after the peer review process, other than those that are disclosed by the journal. You should also understand that plagiarism during the review process is considered misconduct. 
• Declare all potential conflicts of interest, seeking advice from the journal if unsure whether something constitutes a relevant interest. If such conflicts could influence the evaluation, reviewers should decline the invitation. 
• Not allow your reviews to be influenced by the origins of a manuscript, the nationality, religious or political beliefs, gender or other characteristics of the authors, or by commercial considerations; 
• Alert editors to any suspected similarities with another article. 
• Be objective and constructive in their reviews, refrain from being hostile and from making slanderous or derogatory personal comments.