While live-fire cooking is difficult indoors without heavy-duty ventilation, it is possible to simulate some of the effects of a live-fire grill with indoor equipment. The simplest design is known as a grill pan, which is a type of heavy frying pan with raised grill lines to hold the food off the floor of the pan and allow drippings to run off. Though they have only become popular since the 1990s, such pans are widely recommended for apartment dwellers and people who live in areas where outdoor cooking is impractical for weather reasons.