The episode "The End" is the final episode in the television series LOST. The flash-sideways timeline is explained, and the fate of the remaining people on the Island is revealed. Many characters from past seasons rejoin the main cast in this episode.
Picking up from What They Died For, Jack is the new protector of the Island, and his first order of business is killing The Man in Black who remains in the guise of John Locke. In order to do this, Jack must use Desmond to enter the Source and "pull the plug" on the power of the Island, rendering The Man in Black and Jack himself, mortal. This is the final confrontation in the original timeline.
The other remaining Islanders make their way to the The Ajira Plane, still on Hydra Island, to escape.
In the Flash Sideways timeline, all of the Islanders converge on a concert which features the music of Daniel Widmore and Drive Shaft. As each character meets others from the Island, sharing similar experiences, they begin to "remember" the events on the Island. This culminates to the final scene in a Church where Christian Shephard's funeral is being held.
Most of the remaining mysteries of the show are explained.