Potluck dinners are events where the attendees bring a dish to a meal. Potluck dinners are often organized by religious or community groups, since they simplify the meal planning and distribute the costs among the participants. Smaller, more informal get-togethers with distributed food preparation may also be called potlucks. The only traditional rule is that each dish be large enough to be shared among a good portion (but not necessarily all) of the anticipated guests. In some cases each participant agrees ahead of time to bring a single course, and the result is a multi-course meal. Guests may bring in any form of food, ranging from the main course to desserts. In the United States, potlucks are associated with crockpot dishes, casseroles (often called hot dishes in the upper Midwest), dessert bars, and jello salads. Traditionally, potlucks were a simple combination of dishes brought together by event attendees without a general theme. However, recent times have seen the growth of themed dinners for parties or special occasions.