Titanium White, developed in 1919, is the most commonly used white. It is a highly-durable, all-purpose white paint, favored for its opacity, brilliant whiteness and brightness. The primary pigment used in Titanium White is titanium dioxide, which, in its pure form, reflects 97.2% of all available light. Titanium White’s masstone, while neither warm nor cool, lies between Lead White and Zinc White. Titanium White has a slower drying time than Lead White but a faster drying time than Zinc White. It is truly an all-purpose white color.
Titanium White's tinting strength is superior to any of the other whites and it is less prone to yellowing. Artists favor it because it is also good for direct painting. When using Titanium White, artists are advised to not use too much of it, because it has a tendency to overpower other colors.
According to wiseGeek, "In oil painting, Titanium White leaves a yucky, spongy film once dry. For this reason, titanium dioxide and zinc oxide are often blended to achieve a better finish. This mixture is often called titanium-zinc white." Well, I didn't know that. So I checked my tube of Winsor and Newton oil Titanium White and it is, indeed, mixed with zinc oxide.
Besides paint, titanium dioxide is used to “color” an endless line of products. It is found in correction fluid, toothpaste, road-marking paints, white fireworks, coatings, plastics, inks, sunblock and tattoo pigments.