What is plain clothes?

Plain clothes: clothes in white or other simple colors without patterns and other colors. In the current design standards, there is actually no such a specific concept as "plain color", but in color classification, plain color is actually a colorless system, and people are used to calling it "plain color". Colors can be divided into colored and achromatic colors. Some colors have certain or certain hues in the spectrum, which are collectively called hues, while achromatic colors have no hues, such as black and white. Various gradations of gray formed in the process of changing from black to white also belong to achromatic colors, which are called plain colors.