The deck is the wood part of the skatebard(if you didn't already know that). This hub will help you find the right deck for you.

 For technical and street riding you would need about a 7.5"-8"wide decks. This well help you do flip tricks, grinds, and other stuff like that a bit easier.

 If you like to skate in half pipes or pools or at a skate park your deck should be about 8.25" to about 8.5" wide. The wider the deck the more stable it is.

 If you like to skate stree and park your deck should be any where around 8" wide.

 If you just like to ride around and go fast you could get any size of skateboard deck or a longboard.