To put all the parts of the skateboard together, there is a need for hardware. These are bolts and nuts that go through the opening in the deck and through the openings in the trucks. This is how your trucks are secured under your skateboard. The biggest differences between this hardware is the length of the bolts (mainly expressed in inches (")) and the types of bolts.
For example, there are Phillips head bolts, which are made for a cross screwdriver. In contrast, there are Allen head bolts, which are made for an Allen wrench.