I was invited to a small get-together with some friends of mine and it soon turned into a mini-techno-rave. (and by that I mean about 5 of us in a dark screened-in porch blasting DDR and other techno muzac) Then, somebody pulled out the glowsticks... Long story short, I got stuck with the glow-necklaces, which, while still cool, aren't really that exciting just hanging on your neck, I start swinging them around and made cool-looking designs. After the party I researched a bit because (circles get old really fast and) I wanted to be ready for next time.
Poi originated with the Maori People of New Zealand. While methods and materials have changed, the prinicipal is basically the same: swing something around fast enough so that the blur makes a pretty pattern.
Modern variances are: Performance/Ribbon Poi, Glow Poi, and Fire Poi (as well as Diamond, Ruby, Sapphire... no, not really)
Techniques learned in one easily transfer to another, so Practice Poi are used when... well... Practicing. They are usually made with something soft, but must be dense/massive enough to swing well. Popular ones are bean-filled gym socks and tennis-balls on the ends of strings.
There are quite a few instructables on how to make them already, so I won't cover that here.
Other Poi Instructables
I will attempt to teach you some VERY basic moves. They should be enough to either 1) spark your interest and lead you to pursue greater learning ... Or 2) convince you that this really isn't your thing and that you can serve humanity better in other ways.
Either way, I hope you enjoy.