Game Jams come in many forms, and include all levels of game developers. Most Game Jams are comprised of amateur developers, but large game developers, such as Double Fine (Amnesia Fortnight) have been known to hold internal Game Jams.
Game Jams are also not limited to a single location. There are notable examples of Game Jams where teams participate worldwide. Examples of these include the Global Game Jam, Molyjam, and Ludum Dare.