The plastic shopping bag appears to be part of a cycle. Before the 1800s, shopping bags did not exist; shoppers used baskets or had the merchant deliver to their homes, just as online shopping delivery does so today. Paper bags came in when they became easy and cost-effective to mass produce, only to themselves be replaced by plastic bags. As the environmental cost of plastic bags starts to outweigh the benefit, much of the demand for single-use plastic bags has fallen. There is no requirement.