Colours

Autumnal Colours

The colours of the leaves are defined by many factors (temperature, light, humidity, etc). The three most common pigments in leaves are:

Chlorophyll (greens)

Carotenoid (yellows, oranges and browns)
Anthocyanins (reds)

I'm not going to elaborate here because it is a really complex subject but if you are after more information Wikipedia has a good article about the colours of leaves.