Ever wonder what the symbols, seals, or sets of letters like "UL" or "CSA" on the back of your smoke detector, microwave oven, hair dryer, or air conditioner mean? Known as certification marks, these logos and acronyms indicate that a consumer product has been tested by this third-party laboratory and that it is certified to meet nationally recognized standards for that type of product. Certification laboratories, like Underwriters Laboratories Inc. (UL, shown)) and the Canadian Standards Association (CSA), must prove that they have the technology and ability to test a product to the applicable standards.