White means safety, purity, and cleanliness. As opposed to black, white usually has a positive connotation. White can represent a successful beginning. In heraldry, white depicts faith and purity.
In advertising, white is associated with coolness and cleanliness because it's the color of snow. You can use white to suggest simplicity in high-tech products. White is an appropriate color for charitable organizations; angels are usually imagined wearing white clothes.