Studying Precalculus is like crossing a bridge.  You’re between two worlds, one old, one new.  On one side of the bridge is a land of kingdoms with which you are familiar: Arithmetic, Algebra, Geometry, and Trigonometry... On the other side is a wonderous new place: Calculus.

The bridge itself is Precalculus. Anyone wishing to cross the bridge must serve an apprenticeship among the well-worn shop benches in the guilds of Arithmetic, Algebra, Geometry, and Trigonometry. This is how one pays the toll. This is the only way to reach the opportunities on the other side.

Of course you are eager to cross, and see for yourself this wonderous place. But you must be patient...

-adapted from W. Mueller

http://www.wmueller.com/precalculus/whatis/0.htmlz