cur·rent \ˈkər-ənt, ˈkə-rənt\

noun
1 a : the part of a fluid body (as air or water) moving continuously in a certain direction
b : the swiftest part of a stream
c : a tidal or nontidal movement of lake or ocean water
d : flow marked by force or strength
2 a : a tendency or course of events that is usually the result of an interplay of forces
b : a prevailing mood : strain
3 : a flow of electric charge; also : the rate of such flow

I deal with current every day. We all do. See definitions 1, 2, and 3. We hear about the current trends in fashion, electrical current flows through every gadget we use, from iPods to refrigerators, and as fishermen, of all kinds, be it fly or bait/lure, our success depends on our ability to read the current of the river, lake, or ocean we happen to be in. One section of river might have a pretty constant, even flow, while another might have several micro currents, all fighting to destroy that perfect dead drift of the fly that picky trout like to see. Pocket water presents all sorts of changing currents.
That is one aspect of the sport that I just love: trying to figure out what's happening on the surface, and below it, and then casting my line out there, and hoping I read things right. If I did, then I know if there's a fish there, I have a good chance of provoking a strike. If I didn't, or if I make a poor cast, and that fly drags at all, then I know that fish is likely laughing and mocking. When I've read the river right, and I'm prospecting for trout, even if I don't hook into anything, I come away satisfied. If, on the other hand, I see a rising fish, and don't get my tuck cast just right, or screw up my mend, not much on the river frustrates me more.