An Air Barrier is a tested component or material that is installed to control the unintended movement of air into and out of a building enclosure. In order to qualify, the tested component should have an air permeance of less than 0.02 L/(s•m2) @ 75 Pa (0.004 cfm/ft2 @ 1.57 lb/ft2) or equivelant to a 1/2 sheet of drywall. Keep in mind that air permeance relates to how much air can migrate through a material, whereas air leakage generally describes how much air passes through such items, holes, and gaps.
