Plastic bags are made primarily from plastics—common materials include polypropylene, polyester, and nylon—and are an indispensable part of everyday life, often used to carry other items. Their affordability, extreme lightness, large capacity, and ease of storage have led to their widespread use. There are many types of plastic bags, each suited to a variety of applications.

1. Vest‑style bags, also known as convenience bags, are made of single‑layer polyethylene. They are commonly found in markets and supermarkets, including takeout bags, and are a very familiar type of plastic bag in everyday life. Easy to produce and widely used, they offer great convenience; however, due to their environmental impact, many countries have implemented plastic‑reduction policies, banning the manufacture of vest‑style bags thinner than 2.5 mils to curb their consumption. Moreover, the bags most often seen on the market—typically white, red, or yellow—are frequently substandard and can harm both the environment and human health.

2. Supermarket shopping bags and roll‑type bags with a single‑layer material structure. Most packaging bags currently used in large supermarkets are either biodegradable or food‑grade, minimizing environmental impact and posing no harm to human health. However, these biodegradable bags are more expensive, resulting in lower adoption rates in the market.

3. Trash bags and courier bags are primarily made of single-layer PE. Based on the raw material, they can be categorized as follows: new‑material courier bags, semi‑new‑material courier bags, and recycled‑material courier bags. Currently, semi‑new and recycled materials are most common, as they are cost‑effective and promote material recycling. PE is safe, non‑toxic, and odorless; however, after recycling, it often contains impurities, so it is suitable only for use as trash bags or courier bags.

4. Composite packaging bags—used for food, pharmaceuticals, clothing, liquids, tools, daily necessities, and more—are ubiquitous in everyday life. These bags feature a multi-layer structure that enhances sealing and water resistance, while delivering vibrant, eye‑catching print colors. Most products displayed on supermarket and retail shelves are packaged in composite materials, which are safe, non‑toxic, and comply with national standards.