Master classes can be given in any discipline, but they are more commonly used in more advanced music education. Perhaps that’s because, according to Wikipedia, famous composer Franz Liszt invented the format.
The difference between a normal class and a master class is the format. They often take place in front of an audience and can run anywhere from two to five hours long while each student get a turn performing for “the master.” Usually, the student performs, the master advises him or her, and then the student gets a chance to perform again while incorporating the advice given. Sometimes, the student might be asked to play or sing one passage repeatedly to get it right.
What’s cool about the master class format is that each student can benefit from the comments on all the other students’ performances.
“Often, a touring performer will give a master class the day before, or the day of, their performance in a particular city. Giving a master class before a concert provides both artistic stimulation for the performer and a means of obtaining a larger audience.
“Aspiring classical musicians, and their teachers, typically consider master classes to be one of the most effective means of musical development, along with competitions, examinations, and practice.”