WHY is blood taken from the ring finger?

The fingertips are easily accessible, hairless, rich in blood vessels, easy to disinfect, and even squeeze if necessary. The skin on the ring finger is thinner than on the thumb, index and middle finger, and contains fewer nerve endings, including pain receptors. 

The little finger, on the other hand, is closely connected to the wrist, so if an infection is introduced into a wound on the little finger, it can spread to the bend of the wrist!