The word Viniyoga comes from Sanskrit, using the word
Yoga plus the prefix vi and ni, which imply “special application”.
The term isn’t really used for Yoga alone, it’s actually used
whenever you want to define something as having a specific
application depending on the context.

Therefore, in this “style” of yoga, the application of the
techniques is always done according to the specific situation of
the student. Viniyoga practice is always dependent on the question
“who is the student?” Viniyoga comes from the direct teachings of
T. Krishnamacharya, who is considered the
grandfather of Yoga as we know it in the West.

He taught Pattabi
Jois (who went on to teach what today is known in the west as
Ashtanga Vinyasa Yoga), and B.K.S. Iyengar, the Master behind
Iyengar Yoga