Shime-Waza (Choking Techniques) is one of the groups of Katamewaza (Grappling Techniques)

The execution of choke is in practice a subtle art because of the potential danger for the opponent. There are three fundamental manners for chokes: compression of the neck-veins which restricts the flow of blood and oxygen to the brain, compression of the trachea,and compression of the chest and the lungs which prevents breathing.

Additional resources:

Pictures of Choking Techniques
Principles of Judo Choking Techniques by Neil Ohlenkamp
The Challenges of Shimewaza by Elie Morrell
How Safe is Choking in Judo? by E.K. Koiwai, M.D.
The Safety of Judo Chokes by Leonard I. Lapinsohm, M.D.
Emergency Care for Chokeholds by John Boulay
Deaths Allegedly Caused by the Use of Choke Holds by E.K. Koiwai, M.D.
The Challenges of Shimewaza by Elie A. Morrell


Also check out Pinning Techniques (Osaewaza) and Joint Locks (Kansetsuwaza).

Or vist animation Throwing Techniques (Nagewaza) page. 


sankaku Choking Techniques (Shime-Waza)


Pain is the best instructor, but no one wants to go to his class.