Short answers, pulled from the story.
The word audit comes from Latin and translates to he or she hears. This origin defines the entire practice in higher education where a student has heard the lectures without being tested on what they learned.
Individuals choose auditing for self-enrichment and academic exploration because they seek enjoyment rather than credit. Avoiding the risk of a poor grade is another common motivation since these students do not desire academic credit for their time.
Colleges and universities generally offer auditing options while secondary schools rarely provide this choice to students. Grammar schools typically do not allow non-credit enrollment but higher learning institutions treat auditing as a formal option.
Standard auditing arrangements involve no assessment of performance and no grade gets awarded to the student who audits. The individual receives teaching but faces no testing so the lack of evaluation defines the core mechanic of the process.
References from 2010 confirm its established status in academia after schools have adapted policies to accommodate non-credit learners over decades. The term now appears in academic administration records globally with universities maintaining specific guidelines for those choosing this path.