Basic Construction
Simple 3D solids (cubes, cylinders, etc.) are referred to as brushes inside the Hammer editor. These objects are the basic building blocks for all maps built for Source. Floors, walls and ceilings—in short all geometry other than models—consist of brushes.
Tip: If your object does not appear textured already, click on the Camera view and go to View > 3D Textured Polygons to view a textured version of your object.