I wish you could've seen it in the original super-giant widescreen Cinerama. It would still have been confusing, but it would have been prettier. Briefly: an alien intelligence places a "monolith" on Earth to give pre-humans' intelligence a kick-start to start them on the path to the next level. Then, in 2001, humans find a similar monolith buried on the moon. It was put there because for humans to find it there, they'd have to have advanced to a point where they'd have technology to get them to the moon. The monolith on the moon sent a powerful radio signal toward Jupiter (Saturn in the novel). Humans built a spacecraft to go to Saturn. On the way, the computer HAL malfunctions and starts killing off the humans. Only HAL knows the real purpose of the mission, which is to investigate extraterrestrial intelligence. HAL is supposed to have revealed that once the spacecraft got to Jupiter space. The last human alive disconnects HAL, gets in a spacepod and heads toward the immense version of the monolith that is orbiting Jupiter. He and his pod "fall through" the monolith, like it's some sort of wormhole. For the rest of his life he is schooled by the alien intelligence. At the end of his life, he is transformed into a fetus-like being and sent back to Earth to start mankind on the next evolutionary step. In the novel, he was sent back to Earth to prevent a nuclear war, but it's not specified in the movie.

Go and watch the next movie 2010, it ties up a lot of the "huh?" left over from 2001.

dont worry the first time i saw it i was stoned and i didnt get it either - i have been clean and sober for over 19 years now and i still dont get it

not all the tea in china or pot in columbia will help you and me ever understand that movie. it's out there like, "a clockwork orange". i could watch them 100 times and maybe get them, but, then, i've wasted 200 hours of my life or each silly movie. i'll stick with shrek!