Oh, you don't know it? It was a movie that made the idea of "being trapped in a computer and all our reality is just a simulation" popular. There were probably others who did the same plot before, but that one had some new filming tricks that made it a big global hit.

The story was about a man who got the option to "wake up" from the fake reality, and how he and his allies fight the computer to safe the others from the Matrix as well.