Science fair projects are based on either thematic or academic level subjects. The science fairs may be professional, student, or introductory level depending on the promoter of the event and relevant subjects. Many school science fair projects have set areas of subject matter, like biology, applied physics, or other areas of academic studies. The upper level science fairs are advanced, experimental and/or college level technological events, with a high degree of presentation values and requirements for subject content. Science fairs are held at all academic levels and usually operate with those levels as their definition.