Yoga is the state in which one recognizes the "reality in itself" and no longer confuses it with the subconscious illustrations of its mind (memory, ideas, categories, etc.). The prerequisite is letting go of the idea "I can see what is" because without yoga you can only see a greatly reduced and distorted picture of reality, an illusion.
This leads to the reduction of all forms of confirmation and suffering, which inevitably result from the wrong view.
Yoga Exercise is exploring and approaching this condition.
Yoga tradition is a collection of techniques that have been tested, researched and passed on over many generations of teachers and students.