The word seminar is derived, like seminal, from the word semen. Stop laughing. The reason for this is not because seminars were originally entirely conducted by men, nor is it because seminars were often held in brothels; they were not. The reason is that semen is Latin for seed, and a seed is the beginning of something bigger. This aptly describes the method of teaching an academic seminar adopts.
Usually a professor, a lecturer or the postgraduate running the seminar will provide a title, a question, a problem or set of problems for a group of students to discuss and prepare answers for. Sometimes this is given in advance, sometimes only when they are already together. It does not matter. The purpose of the title is to stimulate a discussion, to enable conversation to naturally broaden knowledge, to incite criticism and analysis, in short, to begin something larger. Like a seed. Like semen.
The advantage of seminars is that they enable problems to be spotted before it matters; a student may believe they understand a subject, but until they explain it, they can never be certain. Likewise, a student may think they know nothing of a topic, but when they talk about it, it suddenly makes sense. Seminars provide an environment in which this is encouraged, in which the conversation is not in danger of moving off topic, as it would be in a social conversation. They stimulate the growth of the students.
Seminars are popular in universities with smaller student-staff ratios; since as a rule the smaller the class size, the more productive the discussion. Most people dislike talking to large groups &mdash if there are only a few people present, they feel more compelled to speak. This gives them confidence in themselves. Often there are no right answers; speaking in seminars helps to confirm this.
The disadvantage of seminars is that they are often held at unreasonable hours in the morning.