Extra dimensions

I learned in science class that there are actually more than four dimensions (and something to do with string?)  What are they?  And is there a way to see them?

Oh god.  I don't know much about this, so take this with big grains of salt, but...
The idea is that the universe is made up of tons and tons of tiny little loops (or strings) that are oscillating in interesting ways.  These things are smaller than quarks though, so way beyond what we can measure or see or interact with at all.  Therefore, this is kind of an untestable theory and despite being a nice theory, may yet prove to be total bullshit, so don't freak out about it too much okay?

For this so-called string-theory to work, I believe the strings have to exist inside of tiny little curled-up folds in space-time that have much higher dimensions.  Like 20 or something ridiculous like that.  Now bear in mind, this means that there could be other dimensions gibbering about at very small scales, but at this macroscopic scale, we can't see shit.

If this talk of dimensions excites and inflames your imagination, you should read a book called Flatland as it's pretty cool.