In academia, an audit is an educational term for the completion of a course of study for which no assessment of the performance of the student is made nor grade awarded.
In this case, 'audit' indicates that the individual merely has received teaching, rather than being evaluated as having achieved a given standard of knowledge of the subject.
In other words, the audit student has experienced the course, but has not been assessed.
[2] Sometimes this technique is employed by individuals who wish to take a specific course without the risk of under-performance resulting in a poor or failing grade.
This may be helpful when reviewing a long-unstudied subject, or when first beginning or exploring the study of a discipline where one has little experience or confidence.