Trying to define white as a colour used in website design perhaps seems a little illogical since white is what you get when you add nothing to an area.
White is the opposite of black, and as such it represents lightness in contrast with darkness. It is the colour most associated with innocence, perfection, honesty, newness and new beginnings and neutrality.
The colour white is also associated with cleanliness, which in turn is associated with minimalism in all forms of design, including web design.