The RGB color space is the color space used by computers, graphics cards and monitors or LCDs: It consists of three components, red, green and blue, the so-called base colors.
A color then is obtained by mixing the three base colors. Depending on how much you take from each base color, you can create all colors which a computer/monitor can display.
So if you take nothing from any component, you’ll get black.
If you mix red and green, you’ll get yellow.
If you mix red and blue, you’ll get magenta.
And if you mix all three base colors with full intensity, you’ll get white.
So by mixing the base colors in different intensities, you can create your color.
Now one can draw a color space, i.e. a three dimensional object. And because all three components are equal in their importance, this color space can be visualized as a cube.
Unfortunately you cannot rotate the cube to see it from all sides.
So I created the following slices: They show you how the top of the cube looks like if you cut it off horizontally.
So the slices show you what colors are possible if you set the green part to a fixed value (the slice value) and play around with red and blue.