Modern trade shows attract large crowds from within the general public. Air shows often provide a number of events. They will feature demonstrations that will attract potential customers. The events are often paid for by the fees charged to the professional vendors for space at the show. The amount they pay is determined by the area and size of their booth. Larger booths and heavy traffic areas mean the vendor will pay more. While this is often a huge expense for the vendor, many make a large profit and return each year. This is because the featured events draw a great many people. The holiday atmosphere also encourages people to spend more money.