"What is the Matrix?" "The Matrix is the world that has been pulled over your eyes to blind you from the truth." 

The original "Matrix" is a science fiction/action film written and directed by Larry and Andy Wachowski and starring Keanu Reeves, Laurence Fishburne, Carrie-Anne Moss and Hugo Weaving. It was first released in the USA on March 31, 1999, and is the first entry in the Matrix series of films, comics, video games and animation. 

The film describes a world in which the Matrix is an artificial reality created by sentient machines in order to pacify, subdue and make use of the human population as an energy source by growing them and connecting them to the Matrix with cybernetic implants. 

It contains numerous references to the cyberpunk and hacker subcultures; philosophical and religious ideas, including Socratic and Platonic idealism; and homages to Hong Kong action movies and Japanese animation.

Link: Wikipedia: The Matrix