The keystone is the center stone or masonry unit at the apex of an arch.

In North America the material has largely been replaced by concrete masonry units.

Stretcher - The typical course style, masonry units are laid with their face parallel to the wall and the long dimension outwards.

Soldier - Used mainly for decorative purposes as its upright nature does not lend itself to the compressive strength of a masonry unit.

A wythe is a continuous vertical section of masonry one unit in thickness.

Concrete masonry units may be formulated with special aggregates to produce specific colors or textures for finish use.

There are about 3,000 bottles used as masonry units with railroad ties used as the framing structure.

The process of placing a masonry unit in a mortar bed causes the mortar to be extruded between units.

Removal of old mortar between joints is done carefully to avoid damage to masonry units.

The use of Portland cement mortar for repointing on older buildings with soft masonry units can cause significant damage due to physical incompatibilities.