Surfboard Terminology

Outline and Tails

The outline, also called plan shape, is the overall body shape of the board from end to end. A big wave gun board will have long, gentle sweeping curved sides. The curvature of the sides is a factor in determining the way the board turns. Big wave boards are used for long gentle turns. Shorter boards with shorter, more rounded curves will turn tighter. The plan shape is what determines the type of board. Shapes include short boards, fishes, long boards, fun boards and hybrids.
Common tails include squash, square, round, pin, and swallow. In general, the wider the tail, the more aggressively it can be used for turns, square being widest and pin most narrow. Swallow tails enable deep cutting turns while round tails allow smooth, fluid turns.

Surfboard Tail Types

Width

The wider the surfboard the more stable it will be, as well as giving it extra planning area. Tail width will determine how loose your board is. Shortboards tend to have wider tails while guns will have narrower tails for mote drive and stiffness
Rails and Edges

The side edges of the board are its rails, or edges. Seen from the side, they can be thin or thick. Thin rails means the deck slopes in as it reaches the edges. Thick, or full rails make a flat, boxy deck. Thin rails (good for beginners) are more responsive to long smooth turns when you shift your weight, while fuller rails produce short, tight turns on small waves. Rail thickness can vary throughout the length of the board, from nose to tail.

Bottom Contour

The bottom contour a the curve from rail to rail and is perhaps the most complex and debatable element surfboard design.

CONCAVE:
Feeds water under your board and out through the tail, giving it more speed and acceleration. Varieties include single concave, double concave and single to double concave (single under the front root feeding into a double under the back foot).
CHANNELS:
Designed primarily for clean surf, channels will give your board excellent speed and are great for power carves. The negative is they can tend to 'track' on the wave face if too deep.
VEE:

Designed to guide the board from rail to rail quickly, the Vee design’s increased movement compensates its lack in speed.

Rocker

When you look at a board from the side, this is the curve that lifts the nose and tail up. It can vary from nose rocker, to midsection rocker and tail kick. Rocker effects the speed and turning capability of the board. More rocker generally means it can make tighter turns. Generally, if you are surfing tight in the pocket or hollow, punchy waves you'll need a surfboard with more rockers. If the waves are fat and slow, then a flatter rocker will be better for maintaining speed through the dead sections.

Fins

A board can have either one, two, three or four fins. Fins direct the flow of water under the board. More fins make a board more stable and easier to keep going in the direction you want. Fewer fins make the board looser in the water and easier to turn. A long board will have large fins to keep it stable while the surfer moves around on the board. Fin number and size generally coordinate with the size of the board and its intended use.
Fins can either be removable or permanently attached. An example of removable fins are Future Fins, FCS, Redfin. Permanent fins are glued on or glassed on. Removable fin systems are convenient for traveling, changing sizes or when fins accidentally snap off. Glassed-on fins look nice and make a good collector's board.