原色是指不能透过其他颜色的混合调配而得出的「基本色」。

以不同比例将原色混合，可以产生出其他的新颜色。以数学的矢量空间来解释色彩系统，则原色在空间内可作为一组基底矢量，并且能组合出一个「色彩空间」。由于人类肉眼有三种不同颜色的感光体，因此所见的色彩空间通常可以由三种基本色所表达，这三种颜色被称为「三原色」。一般来说叠加型的三原色是红色、绿色、蓝色（又称三基色，用于电视机、投影仪等显示设备）；而消减型的三原色是品红色、黄色、青色（用于书本、杂志等的印刷）。

Primary colors are sets of colors that can be combined to make a useful range of colors. For human applications, three primary colors are typically used, since human color vision is usually trichromatic.

For additive combination of colors, as in overlapping projected lights or in electronic visual displays, the primary colors normally used are red, green, and blue. For a subtractive combination of colors, as in mixing of pigments or dyes for printing, the colors magenta, yellow, and cyan are normally used. However, red, yellow, and blue are commonly used as primaries when painting or drawing. See RGB color model, CMYK color model, and RYB color model for more on these popular sets of primary colors.