UL is short for Underwriter Laboratories Inc. The UL Safety Test Institute is the most authoritative in the United States, and it is also a large non-governmental organization engaged in safety testing and identification in the industry. It is an independent, non-profit, professional agency that conducts tests for public safety. It uses scientific testing methods to study and determine the extent to which materials, devices, products, equipment, buildings, etc. are hazardous and hazardous to life and property; determine, write, and issue corresponding standards and help reduce and prevent life Information on property loss, and conduct fact-finding business. In short, it is mainly engaged in product safety certification and operating safety certification business, and its ultimate purpose is to obtain products with a fair level of security for the market, and to contribute to ensuring personal health and property safety. In terms of product safety certification as an effective means to remove technical barriers to international trade, UL also plays an active role in promoting the development of international trade.

     UL is an abbreviation of Underwriteries Laboratories Inc. Founded in 1894, he is a non-profit product safety testing and certification organization. There are more than 50 laboratories worldwide and about 6,000 employees. Thousands of products pass the UL certification and use the UL mark every year. At present, UL has more than 800 sets of standards, of which 75% are adopted by the American National Standards Institute (ANSI: American National Standard Institute). Currently, UL has five laboratories in the United States, headquartered in Northbrook, North Chicago, and has established corresponding laboratories in Taiwan and Hong Kong.

There are three types of safety certification: approval, listing, classification, and three different ways of marking (see the figure below)

UL listing service is the most widely known service in UL safety certification. The UL listed mark on the product represents that the manufacturer has let UL test the samples in accordance with the safety standards recognized by the United States. Under reasonable and foreseeable conditions, the samples will not cause fire, electricity leakage and related hazards.

Approved component services are test parts or non-finished products that will be used in UL listed products. UL's approved component services cover millions of plastics, wires and circuit boards, as well as various finished products, or even larger components such as motorcycles or power supplies. UL-rated products are tested for different properties, specified hazard ranges, or specific situations. Generally speaking, most graded products are construction materials or industrial instruments. Graded products include products for industrial or commercial use, and have specified properties when tested, including flammability, hazardous performance or special specifications required by the government.