Like green, purples come in many shades. There are more bluish purples and more reddish purples. Like blue, it is also the most saturated at its darkest. And like both, it comes in both light and dark shades, warmer and cooler hues, and can be vivid or dull.
However, purple is an oddball in the 6 basic colors of the rainbow when it comes to making pleasing color. It can never be used at full saturation outside of very dark values, as it is very bright at full saturation. You will usually want to have all three color channels greater than 0 for purples as a result.
RGB Purple is a very warm purple. And it's pretty saturated as well. At maximum brightness it becomes RGB Magenta, which is very bright and should be avoided at all costs.
General Rules
- The RGB Blue primary is very saturated so never use a fully saturated purple (ergo Green at 0) if it's not very dark.
- Many purples have a higher blue value than they do the red value. If the red is greater than the blue it may potentially be considered a maroon or magenta instead.
Examples coming soon!
Violet
Violet is actually conflated with purple in some circles, and if I had to consider them separate colors violet would be more bluish.
Examples coming soon!
Lavender
Lavender is a light and pale purple. There isn't much to say about this specific color but it is used often enough to warrant a subcategory here.