The app costs about 3.50. But but you get a fairly extensive app that provides information on litters, knots, flies.
This app comes from North America, accordingly, it is in English. Regional conditions for fishing are related to North America. The description of the fly is extensive and well illustrated. The article, however, are not to be used as a binder recipes - unless it binds so well that a good enough photo as a template. But 'I do not see negatively.
The throws (overhead, double move, roll cast) are described as a video. They are useless in my opinion, to learn, but they show very well the movements.
The nodes are represented extensively and well.
Conclusion: Good reading for quiet hours (bed, toilet, etc.). The Basics to learn of course from a book in connection with a teacher. Greeting.