A Peer Review, also known as a Code Review, is a process used for checking the work performed by one's equals (peers) to ensure it meets specific criteria. Peer review is used in working groups for many professional occupations because it is thought that peers can identify each other's errors quickly and easily, speeding up the time that it takes for mistakes to be identified and corrected. In software development, peer review is sometimes used in code development where a team of coders will have a meeting and go through code line by line (even read it aloud, possibly) to look for errors. Generally, the goal of all peer review processes is to verify whether the work satisfies the specifications for review, identify any deviations from the standards, and provide suggestions for improvements.
Source: https://searchsoftwarequality.techtarget.com/definition/peer-review