What is D/L Method in cricket....???

I just read out an article about how to calculate D/L Method, its not that much easy to calculate it they use a formula to calculate it. It will be 100 at the start of the innings but as overs are completed or wickets fall the “resources remaining" falls. The expected score is the current score plus 235 times the resources remaining divided by 100. The system assumes that the average innings score for an ODI is 235.Z (u, w) = Z0 (w) [1 - exp {-b (w) u}] is the formula used and Z (u, w) is the expected number of runs to be scored in u overs when w wickets have been lost. Z0 (w) is the average total score if an unlimited number of overs were available and when w wickets have been lost. b (w) is a decay constant that varies with w, the number of wickets lost.