Memento Explanation by Christopher Nolan – True Genius – Must Watch

Memento is a 2000 American neo-noir psychological thriller film directed by Christopher Nolan.
Memento is presented as two different sequences of scenes interspersed during the film: a series in black-and-white that is shown chronologically, and a series of color sequences shown in reverse order (simulating in the audience the mental state of the protagonist, who suffers from a anterograde amnesia). The two sequences “meet” at the end of the film, producing one complete and cohesive narrative.
The film was subsequently ranked one of the best films of its decade by several critics and media outlets.

source