Masonry units can be laid in several positions. For example, think of a pair of dice. Each face has a separate number on it. A brick is similar, but there are only 3 faces that are different sizes (since the direct oposite side is the same dimension) and each of those faces can be installed in two directions for a total of six different positions. These positions are called stretcher, header, rowlock, shiner, soldier, and sailer.

http://www.oldvirginiabrick.com/technical/varied_brick_positions.HTML