Soap opera: in the early days of television when this genre became popular, they were aimed at the stay-at-home audience, primarily women. The sponsors of these shows were those of interest to women, aka "homemakers." Naturally, major sponsors included cleaning products and especially dish detergents, i.e., "soap>" This could also include bath soap of course, and tons of commercials revolved about soap for the baby, soap for the shower, soap for the kids' dirty hands, etcetera. There were other types of commercials, of course, for dishwashers, washing machines, vacuum cleaners, cars, cigarettes, and numerous others. BUT...it was easy, convenient and at least 50% accurate to label them "soap operas" because so many sponsors were about cleaning products in general as well as detergent products of some kind, in particular.