Peer review is carried out by sending the manuscript of a scientific article to other experts in the field to check for accuracy and validity. This is good for the credibility of a work because it is checked and verified by multiple people instead of just the authors of the piece. The authors might have biases that impact their analysis of their results, so having people who do not have personal stakes in the results means there is an increased reliability of the research. One of the few cons to this process is that it may take many months (and up to years) for the research to be ready to publish.
