Every rider knows that progression is a big part of riding and improving your bike handling skills allows riders to tackle new, unfamiliar and more challenging terrain. While getting out on the single track can provide opportunities to learn new skills, a mountain bike specific skills park can enhance ones ability to improve more quickly through successive and rapid progression.
A skills park typically consists of various man-made obstacles ranging in size and difficulty. The most popular features are usually wooden "skinnies", bridges, drops, jumps and teeter-totters. If you're lucky enough to have a swimmable pond on site, floating bridges and pond jumps are also in the mix.
A skinny is most often a piece of milled lumber like a 2x4 or 2x6 that is slightly elevated off the ground providing the rider with the experience of balancing their bike across a narrow bridge without falling off. The heights and widths vary depending on the skill levels being targeted but most parks will have multiple sizes to suit every riders abilities. Skinnies provide riders a chance to improve their slow speed balance, tire placement and confidence on technical single track terrain.
Bridges, similar to skinnies are elevated platforms that riders cruise across. Bridges are often found in trails to get riders over creeks, rivers or otherwise boggy areas and can vary in width and length. Bridges are typically 2-3' wide and can range from short creek crossings to hundreds of yards long to bypass swampy lowlands. As such, the skill to confidently make your way across will unlock new areas of trails, previously inaccessible.
Drops and jumps are in a similar category in that they provide "air time" for the rider. A drop is simply a bridge without a ramp down at the end, or there is a gap between the flat of the bridge and the landing area at the end. As suspected, these can range in height and width with most parks having a large variety of sizes. Drops for beginners should range in the 1-6" height with advanced level heights falling in the 5-7' range. Intermediate heights fall in-between. Jumps, as the name suggests, are curved takeoffs that the rider launches off of to gain air time and land smoothly on the other side. Jumps are extremely varied and can be as simple as a smaller roller that can be used to lift the bike off the ground, all the way to massive 20' doubles where the takeoff and landing aren't connected and there is a gap of 20' between the two ends. A good park will have a jump zone where riders can start small and progress their way through the difficulty as they improve. Jump zones will also have multiple jumps in a row of similar size and difficulty so riders can link multiple jumps together.
The last common feature we'll cover here is the teeter totter. And yes, it's probably exactly what you're picturing - a man-made platform with a fulcrum or pivot point in the middle where the rider can enter by riding onto one side, ride up to the pivot point where the teeter will tip towards the ground on the other side and the rider can exit smoothly down the second half of the obstacle. As with any other feature, these will vary in size and difficulty. While not targeted to improve any one specific skill set, they are a fun way to challenge yourself.