Question: What is an additive?
Answer per Dr. Ruth MacDonald (Iowa State University's professor and chair of the Department of Food Science and Human Nutrition):
By definition, an additive is “any substance where its intended use results, or may reasonably be expected to result – directly or indirectly – in its becoming a component or otherwise affecting the characteristics of any food.” This definition includes any substance used in the production, processing, treatment, packaging, transportation or storage of food. In a nutshell, it is anything added to the food to preserve it, increase its level of nutrition or add color or flavor to it.
If you want to know which additives are “Generally Recognized as Safe” (GRAS), as classified by the Food and Drug Administration (FDA), you can find them here. Also, FDA has rules for labeling additives on food packaging. It mandates that “the ingredient list on a food label is the listing of each ingredient in descending order of predominance - meaning that the ingredient that weighs the most is listed first, and the ingredient that weighs the least is listed last. When an approved chemical preservative is added to a food, the ingredient list must include both the common or usual name of the preservative and the function of the preservative by including terms, such as "preservative," "to retard spoilage," "a mold inhibitor," "to help protect flavor," or "to promote color retention."