Needles developed in the late 16th century. Hypodermic needles are used primarily in the intravaneous administration of medication as well as drawing of samples in veins. Benefits include rapid delivery of medication which would otherwise harm the liver or cannot be absorbed orally as in the case of insulin.
Needles also create an extremely sterile environment limiting infections and contamination. Needles come in various sizes or thickness also known as gauge. They range from 7 gauge which is the largest to 33 gauge which is the smallest,21 gauge is the most common size for drawing blood for testing. Needles are made up of a bevelled edge with a cannula alowing the tip to make an easy incision with minimal pain as possible.