Shape is combined with foil and flexibility (materials) to produce the performance characteristics of each fin or fin set. Shapes vary widely, but the terms below are constant and in general the rules around them hold true to most fins. Single fins may have the “template” (shown in blue outlines below) severely “cut away” and “raked” to change the performance and ride characteristics of the board. Quads use combinations of upright and swept sets. In ALL cases the fins work with the shape/rails of the board to produce the final outcomes/capabilities of the board.
No fins can fix a poorly shaped board, and a great board may suffer from miss-matched fins. Learn the terms so you can dig for information at the shop or with your SUP outfitter, and get the right setup(s) for your goals/conditions on the water.