Components are the ingredients that make up a mixture. Using a mixtures design, you can determine the relative proportion of each component that optimizes the response. Mixture experiments commonly occur in food-processing, refining, or the manufacturing of chemicals.
Suppose you want to study how the proportions of three components in a household deodorizer affect the acceptance of the product based on scent. The three components are rose oil, tangerine oil, and neroli oil. You create a mixture design and analyze the results on a trace plot, with a higher value on the vertical scale representing a more desirable scent.