The Fermi Paradox: Where are all the Aliens?

The drake equation states that the universe is teeming with intelligent extraterrestrial civilizations, but we cannot find alien life.
A short documentary explaining solutions to the Fermi paradox.
The Fermi paradox, named after the physicist Enrico Fermi, is the apparent disparity between the high probability estimates for intelligent civilizations, and the lack of evidence.
In simpler terms, if we are so sure that they exist, then where are they?