The Duckworth–Lewis (DL) method is a mathematical formulation designed to calculate the target score for the team batting second in a limited overs cricket match interrupted by weather or other circumstances. It is generally accepted to be the most accurate method of setting a target score. The DL method was devised by two English statisticians, Frank Duckworth and Tony Lewis. After their retirements Professor Steven Stern became the custodian of the method. In November 2014, it was renamed the Duckworth–Lewis–Stern method (or D/L/S method)

 

The basic principle is that each team in a limited-overs match has two resources available with which to score runs: wickets remaining, and overs to play. Where overs are lost, setting an adjusted target for the team batting second is not as simple as reducing the run target proportionally to the loss in overs, because a team with ten wickets in hand and 25 overs to bat can be expected to play more aggressively than if they had ten wickets and a full 50 overs, for example, and can consequently achieve a higher run rate. The Duckworth–Lewis method is an attempt to set a statistically fair target for the second team’s innings, based on the score achieved by the first team, taking their wickets lost and overs played into account. This method has been nomenclatured as Duckworth–Lewis–Stern method (or DLS method)

It is still a matter of concern  that most news papers/portals/websites report the rain affected match results under DL Method and not DLS Method even though the DL Method has  undergone a change as DLS Method from November 2014 – about two and a half  years back