A relatively simple question for sure; however, answers to this question become so standard that no-one stops to think of the implications of colors or how they definitely reflect and contribute to moods.
The colors of the rainbow are a good place to start. Everyone is familiar with the rhyme..."red and yellow..." and so on but a rainbow covers
the entire spectrum of colors of visible light, from the longest wavelength, red, to the shortest wavelength, violet.
Due to the way we see color, it actually takes millions of droplets of rain, as reflected by the sun, to create color. So we really should appreciate color as it is far more than just synthetic colors created by very talented people and which adds dimensions to our lives that we are almost unaware of.
I hope this is not too philosophical but maybe those of us who "think black" or who wear primarily the same color because "it suits my eyes," or "it makes me look slim" and so on will reach out and have a "yellow" day or a mixed colors day or something.
I have a favorite color for the car - white; (doesn't show dirt or scratches!), favorite colors for the bedroom (gray, white with red accessories - looks amazing!), favorite color for the garden (green but bright green.) The garden umbrella, crockery, even the knives and forks's handles, place mats, etc with black charger plates and black ,green and white cushions- all come together to create a space everyone wants to hang out in. I could probably go on all day!
I agree purple is a great color too.
Have fun with color!