UL (Underwriters Laboratories) is a safety consulting and certification company based in Northbrook, Illinois "Northbrook (Illinois)"). It has offices in 46 countries. UL was established in 1894 and has been involved in analyzing the safety of many of the new technologies of the last century, particularly the public adoption of electricity and the development of safety standards for electrical appliances and components.

UL provides safety-related certification, validation, testing, inspection, auditing, consulting and training services to a wide range of customers, including manufacturers, retailers, policy makers, regulators, utilities and consumers.

UL is one of several companies authorized to conduct safety testing by the US federal agency Occupational Safety and Health Administration (OSHA). OSHA maintains a list of approved laboratories, which are called Nationally Recognized Testing Laboratories.

Underwriters Laboratories Inc. was founded in 1893 by William Henry Merrill. Early in his career as an electrical engineer in Boston, Merrill was sent by fire insurance companies to the Electric Building at the World's Columbian Exposition in Chicago in 1893 to investigate and estimate risks. In order to determine and mitigate risks, Merrill found it necessary to conduct testing on the building's construction materials. Realizing the growing potential of this field, Merrill remained in Chicago to found Underwriters Laboratories.[2]​.

Merrill began developing standards, initiating tests, designing equipment, and discovering risks. UL published its first standard, "Tin-Coated Fire Doors," in 1903. In 1905, UL established a labeling service for certain categories of products that required more frequent inspections. In 1906, UL introduced the UL certification mark to indicate products that passed its tests.

UL has expanded and is now an organization with 64 laboratories, testing and certification facilities for customers in 104 countries.[3]​ It has evolved from its roots in electrical and fire safety to address broader safety issues, such as hazardous substances, water quality, food safety, performance testing, compliance and safety education, as well as environmental sustainability.[4]​.

Sustainability Standards.

Standards for Electrical and Electronic Products.

Vital Safety Standards.

Standards for Construction Products.

Standards for Industrial Control Equipment.

Standards for Plastic Materials.

Standards for Wire and Cable.

Standards for Canada developed by ULC Standards, a member of the UL family of companies.