There are three main bandhas which are considered our internal body locks.
A bandha is a sustained contraction of a group of muscles that can assist the yoga practitioner in retaining and moving in and out of a pose.
Mula Bandha or root lock is performed by tightening the muscles around the pelvic and perineum area.
Uddiyana Bandha is a contraction of the muscles of the lower abdominal area, considered the most important bandha as it supports our breathing and encourages the development of strong core muscles.
Jalandhara Bandha, throat lock, is achieved by lowering the chin slightly while raising the sternum.