A breast pump is a mechanical evice (powered manually or by electricity) that extracts milk from the breasts of a person who is lactating. The breast pump was invented and patented by Edward Lasker. Mechanically, a breast pump is directly analogous to a milking machine used in commercial dairy production. A misconception is that the breast pump suctions milk out of the breast. A breast pump's job is to trigger the milk-ejection response or let-down. Most pumps achieve this goal by using suction to pull the nipple into the tunnel of the breast shield or flange then release, which counts as one cycle. Thirty to sixty cycles per minute can be expected with better quality electric breast pumps. It is important to note that in most cases the breast pump is not as efficient at removing milk from the breast as the nursing baby.