I have faint light blotches on my legs.i don't normally have them as bad but i went in the sun and they appeared.they aren't really noticeable though?

Rash: If you always have had slightly lighter spots on your legs, they may be spots of vitiligo. If it is more of new occurrence, another possibility is tinea versicolor, which is a fungal infection of the skin, usually more on the upper trunk though that will be more apparent when you tan because that skin will not tan, making the rash more obvious. See your MD to have a look.