There are very few professions that can stand alone without any suppliers. Many use products and services from other companies in order to fulfill their contracts. Professional cleaning companies are an example of this concept. They may supply the people to clean offices or homes, but they must also have their own suppliers. Goods such as cleaning chemicals, brooms and mops are all part of cleaning. Without suppliers, these companies could not function.
Conferences for these professionals might include a large array of display booths. There would be companies in attendance to help them choose a new brand of cleaning chemicals for windows, floors or other areas that require chemical cleaning supplies. Companies that produce mops, brooms and dusters would all be attempting to get a larger share of the market by attending the conference. Even lecturers might attend to help professionals understand how to better market their services or be more environmentally conscious with the chemicals they use at work.