A bandha (Sanskrit: बंध) is a kriyā in Hatha Yoga, being a kind of internal mudra described as a "body lock," to lock the vital energy into the body. Bandha literally means bond, fetter, or "catching hold of".

Mahā Bandha ("the great lock") combines all the other three bandhas, namely:

In Ashtanga Yoga, these three Bandhas are considered to be one of the three key principles of yoga practice.

Mūla bandha is a primary bandha in traditional yoga. The earliest textual mention of mūla bandha is in the 12th century Shaiva Natha text Gorakṣaśataka which defines it as a yogic technique to achieve mastery of breath and to awaken the goddess Kuṇḍalinī.

Mula Bandha (Sanskrit: मूल बंध) is from Mūla, meaning variously root, base, beginning, foundation, origin or cause.

Gorakṣhaśataka defines mūla bandha as:

[The yogi] forces the downward-moving apāna breath to move upwards by means of contraction. Yogis call this mūla bandha, "the root lock." When apāna has turned upwards and reached the orb of fire, then the flame, fanned by the wind, rises high. As a result, fire and apāna reach prāṇa, which is hot by nature. The overheated prāṇa creates a blaze in the body, which heats the sleeping Kuṇḍalinī and wakes her up. Like a snake struck by a stick, she hisses and straightens herself. As if entering a snake-hole, she enters the Brahmā naḍi. Therefore, yogis should maintain the regular practice of mūla bandha. Gorakṣaśataka

Iyengar defines Mūla Bandha as "A posture where the body from the anus to the navel is contracted and lifted up and towards the spine". This is qualified in that the actual muscle contracted is not the sphincter muscle nor the muscle which cessates urination, but the muscle equidistant between the two.