I rarely fish dry flies but plan to a lot more this year. So I was looking for some in depth articles to explain a question i have about dry fly presentation, but didn't find many sources. So i'll come to you guys for some help. When watching a video on dry fly fishing, you see the person stripping in line, and i was wandering if this is to skim the fly across the surface or to pick up the slack as the fly drifts closer. Also, if one is upstream fishing into a downstream hole, how should he present the fly and retrieve. For example, would I just strip line as the fly drifts down into and past the hole?