What does Dapping refer to in Fly Fishing?

Dapping is a very basic fly fishing technique, whereby only the fly is in contact with the water. The leader, tippet and line stay out of the water, in an effort to reduce visibility of anything unnatural looking.

The idea behind dapping is to get the fly to skip across the waves or ripples. A reasonable wind is essential, too little and the fly does not "dapple" properly, too strong and the whole thing becomes very difficult to control. As it is only the fly that touches the water the fish are unaware of any line being attached to it and they seem to find this skipping action of the fly tantalizing and irresistible, indeed, often they will come out of the water and attempt to take the fly in mid-air.