My nephew was told that he needs to wear elastics and headbands with his braces. Is it really necessary?

Elastics are used extensively to either close extraction spaces or to facilitate the relative movement of teeth with respect to one another. Headbands are used to make a section of teeth harder to move against another segment or they be used to move a section of teeth. Another important use is to effect what we called skeletal movement to modify skeletal growth direction. At the end if your orthodontist requires you to wear elastics and headbands, just listen to his/her advice.