A plastic bag is a lightweight, flexible container made from synthetic materials, primarily polyethylene. These bags are commonly used for carrying groceries, shopping items, and other goods due to their convenience and low cost. They come in various sizes and thicknesses, making them suitable for different purposes. Plastic bags are often criticized for their environmental impact, as they can take hundreds of years to decompose. Many countries and cities have implemented bans or fees on single-use plastic bags to encourage the use of reusable alternatives, such as cloth bags or biodegradable bags.