Blend

Blend[{$c_1$, $c_2$}]: represents the color between $c_1$ and $c_2$.
Blend[{$c_1$, $c_2$}, x]: represents the color formed by blending $c_1$ and $c_2$ with
factors 1 - x and x respectively.
Blend[{$c_1$, $c_2$, ..., $c_n$}, x]: blends between the colors $c_1$ to $c_n$ according to the
factor x.

- Blend[{Red, Blue}]
- Blend[{Red, Blue}, 0.3]
- Blend[{Red, Blue, Green}, 0.75]
- Graphics[Table[{Blend[{Red, Green, Blue}, x], Rectangle[{10 x, 0}]}, {x, 0, 1, 1/10}]]
- Graphics[Table[{Blend[{RGBColor[1, 0.5, 0, 0.5], RGBColor[0, 0, 1, 0.5]}, x], Disk[{5x, 0}]}, {x, 0, 1, 1/10}]]