This is a tutorial on characteristics and ratings as used in semiconductor engineering, but these are generally applicable to other technologies. Characteristics are a measureable property of a product. An individual product item characteristic value is measured with the product family specification test conditions applied. The product family specification value limits for that characteristic can be given either as a characteristic minimum or maximum or both or alternatively as a rated value. Product family ratings consist of rated values and (absolute) maximum ratings. Rated values are measureable during the rated value test. Absolute maximum ratings are not directly measureable and have to be verified. The absolute maximum rating test procedure is to first apply the product family specification absolute maximum rating conditions to the product. After that specified product family characteristic values are measured to detect any product degradation. These measured product characteristics should not be outside the degradation limits set by the product family specification.