The trucks on your skateboard are what determine how the board turns, handles, and how stable your ride will be. There are two main types of trucks: straight kingpin trucks (also referred to as traditional kingpin trucks or TKP's) such as Independent and reverse kingpin trucks (RKP's) such as Paris.
The TKP's are used mainly for traditional skateboards like your street deck or pool board and feature a very slight or 0 degree angle on the baseplate, giving you a more responsive turn with less stability at speed and no lean meaning you can get the full range of turn with just your ankles. The RKP's are a newer truck design featuring a different geometry and are generally considered longboard trucks. The RKP's have an angled baseplate, giving you more stability at speed, and a more surf-like, drawn out turn requiring you to actually lean off the board to get the full turn. While both these trucks were designed with a specific purpose in mind, there is nothing to keep you from putting TKP's on a longboard or putting RKP's on a popsicle shape.
***keep in mind that boards with more width require larger trucks and vice versa for boards with less width.