Positiv decks are usually maple, but some are hard birch. They are made using the same laminating process and glue that Powell Peralta boards use. These decks have Positiv’s super slide treatment (SST), which is essentially a plastic lining that makes the board slide more easily. The stuff works, and wax becomes less necessary for slides with these boards.
Another bonus of shopping at an actual skate shop is that you get to see what the boards look like in person. Most skate shops will have a cool wall of boards, and it's fun to just stand there and look at all the graphics. If one jumps out and grabs you, then you can ask the shop owner about the brand, and whether it's a good one. There's nothing wrong at all with buying a skateboard deck because you like the graphics!
Longboards are often 8 to 12 inches longer than a standard skateboard. That added length makes them more stable for long rides or high speed downhill runs. Available in a huge variety of shapes, sizes, and truck mounting options, longboards are highly customizable for many types of riding. If you want to push long distances, skate fast down hills, or are a beginner looking for an easy board for learning to balance, check our Guide to Longboarding for more info.
Most skaters consider width is the most important dimension of the deck. That is measured straight across at the widest point of the deck. Skateboard decks generally range between 7.0 to 10.0 inches depending on the shape of the deck. There are boards that are narrower and wider than that, but they are not common and not practical for all around skating.
Decks come in a variety of shapes and sizes. You can choose a mini-board, a cruiser, a drop-through, or a standard deck for your favorite set of wheels and hardware. Widths range too from a few inches with a 22-inch board to the wide size of a true cruiser. Some decks are flat as possible while others are significantly concave for optimized turning. You can buy a deck with artwork and grip tape already attached for a quick install or you can get a bare-bones wooden deck to truly customize.