Orthodontics is a branch of dentistry [the medical field that deals with the prevention, diagnosis, and treatment of diseases and conditions affecting the teeth and gums] that focuses on correcting and aligning the position of teeth and jaws. It involves the use of braces [devices that are attached to the teeth to straighten them] and other appliances to improve the appearance and function of the teeth.
For example, if someone has crooked teeth or a misaligned bite, they may visit an orthodontist [a dentist specializing in orthodontics] to get braces or other orthodontic treatments.
Very Simple Definition:
Orthodontics is a type of dentistry that helps fix crooked teeth and make them straight. It uses braces and other things to make the teeth look and work better.
For example, if someone has teeth that are not straight, they can go to an orthodontist to get braces and make their teeth straight.