Seminars have many uses.
Some professionals like accountants and real estate professionals have to take continuing education to maintain their licenses and seminars are a quick and easy way to get these CEUs (Continuing Education Units).
Seminars also can serve as quick fixes to fill in the gaps in your business education - a new software can be learned quickly,or a promotion to a new position like supervisor and all the new responsibilities this promotion entails can be covered in a day or two seminar.
Some seminars cover more technical subjects and can keep you up to date on the latest state of the art information without having to devote a whole semester at a local college.
Sometimes seminars can even help you prepare for the job you want to get - professional image seminars can help you learn how to dress for the part and presentation, speaking and writing seminars can help you polish up your skills to make that extra impression that will get you the job.
In the classroom setting, participants in seminar are typically meant to engage in dialogue together in order to build deeper conceptual understandings of texts and ideas. A seminar teacher typically shifts his or her role to that of facilitator or questioner, so that the students can move from passive reception of knowledge to actively constructing meaning and understanding.