There are many different levels available for use in woodworking industry. A laser line level will illuminate a straight line. An aluminum or bamboo level is a rigid rod or bar to make sure a surface parallel to the ground are level. The liquid that fills the vials is called spirit. A bulls eye level is the most common spirit level most DIYers use. The level consists of a straight ruler-like body with a small window in one or more sections containing a vile of liquid with a bubble in it. The main objective of this type of level is to make sure the bubble in the center of the vial indicating it is parallel to the ground. A plumb bob is a brass or metal bulb with a point on the end and is perpendicular to the ground and uses gravity to determine exact vertical alignment.