There are countless fin setup possibilities and each different setup changes the way a board responds and turns. Also the surface area of all fins affects the way the board feels. Lots of fin area provides more control and stability, less fin area gives the board more speed but less control.
These are the most common fin setups:
Typical on longboards and beginner surfboards. Gives the board good stability and control but movements are restricted to drawn out turns with larger arc and straight line surfing. The single fin setup has made a comeback in recent years because of the overall cruisy feel.
Two fins of the same size parallel to each other. This set up provides extra speed and offers good maneuverability in smaller surf conditions. Not so good for top-to-bottom surfing. Usually found on fish boards or boards designed for smaller surf.
Most common fin setups on surfboards today and consists of three fins of the same size. This is the most all-round setup and offers good stability, speed and maneuverability. A thruster set up is the go to choice for most shapers and surfers. It holds well in steep, barreling conditions and allows for vertical surfing and aerial maneuvers.
The Quad setup consists of four fins, two on each side. They offer lots of extra speed and hold very well in steep, large waves. It is a very responsive setup but you will sometimes feel that you lose control in the wave’s face. Overall it produces a looser, skatier board but it is not uncommon to slide out of bottom turns. It takes some time to get used to.