Bandha is a Sanskrit word related to our English words "band","bind", "bond" and "bound." They are particular actions involving pressure or strain on the muscles. Each bandha is a lock, meaning a closing off of part of the interior body. These locks are used in various pranayama and asana practices to tone, cleanse and energize the interior body and organs.
The three important bandhas are:
"Jala" means 'net' and "Dhar" means 'to hold'. In this bandha the network of energy channels or nadis of the body is locked. This bandha is also known as chin lock.
"Moola" means 'root' or 'source' in Sanskrit. The other meaning of moola is also 'anal'. In this yoga bandha anal lock is performed.
In Sanskrit, "Uddiyana" refers to 'flying'. In this bandha the diaphragm is raised up to the thoracic region.