Final answer:
The UL symbol refers to Underwriters Laboratories, which tests and certifies products for safety standards.
Step-by-step explanation:
The UL symbol stands for Underwriters Laboratories, which is a global safety certification company that provides safety-related certification, validation, testing, inspection, auditing, advising and training services. It is known for its testing and certifying of products to ensure that they meet specific safety standards. The UL symbol on a product indicates that UL has tested a representative sample of the product and determined that it meets UL's safety requirements. These requirements are based primarily on UL's own published Standards for Safety.