Fly fishing is perhaps the most technical sport in the fishing world. Fly fishing is all about finesse. Fly fishing is also the primary method of fishing in some countries such as New Zealand for example. So if one visits New Zealand and is invited to fish, most likely one will be offered a fly setup.
Back in the 70s Fenwick started the Fenwick Fly Fishing School to teach anglers how to fly fish. The syllabus was very comprehensive covering everything about fly including techniques, methods, sciences, as well as fly tying. The Fenwick Fly Fishing School has certainly created a lot of fly anglers in America.