Pixol

From ZBrush Info

ZBrush is not just another modeling package. It can create models with amazingly high polygon counts. In ZBrush, you can convert and export this high resolution geometry into the maps, textures and low resolution geometry that you want to use with other programs. ZBrush changes the modeling process. Instead of pushing and pulling points around, you are sculpting digital clay.

ZBrush is also a powerful depth-enabled paint program. In other programs, points on the canvas – the pixels – have color. In ZBrush, points on the canvas also have depth, material and orientation and are called pixols.

Pixols are not drawn just as color on the canvas. They are rendered using their distance, orientation and material information. A change in position of the scene lights will affect their shading on the canvas. Paint strokes can be given the appearance of metal, or wood, or concrete, or mirrors, or of many, many other things.

Pixols combines the simplicity of a 2D painting environment with the power of a 3D application.

The Pixol: The Depth-Enabled Pixel

The Pixel (2D)	The Pixol (2.5D)
Color Information	Color Information
X and Y Position Information	X and Y Position Information
No Depth Information	Z or Depth Information
No Material Information	Material Information

To learn how pixols work click here.