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 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.