Dirtsurfing is the term used to describe the sport of riding a Dirtsurfer brand inline board. This new Australian boardsport is correctly known as inline boarding because Dirtsurfer is a trademark protected brand name.
A Dirtsurfer is composed of an aircraft aluminium tube frame, a laminate or composite deck and two 20in or 16in diameter BMX style bicycle wheels. Footstraps are (optionally) attached to the deck to give more control to the rider. The board is unique in that it incorporates a patented steering geometry where the front wheel pivots from a point in front of and below the axle of the wheel, via the 'Swingarm'. The rider's weight automatically centres and straightens the front wheel, creating stability and control. Another feature of the Dirtsurfer which is not found on other four-wheeled boards is that, much like a bicycle, the stability actually increases with speed, thanks to the gyroscopic action of the large wheels.
The Dirtsurfer can be used as a downhill sport on or off road, using just the power of gravity. The Dirtsurfer may also be "skated" in flat areas. "Skating" the Dirtsurfer means to push yourself forward with one foot while standing on the Dirtsurfer with the other foot the way you would a skateboard. Many Dirtsurfer riders also use a kite, sail or a kitewing, sometimes called wingsurfing to propel the Dirtsurfer in flat areas with adequate wind.
Dirtsurfing with a kite or kitewing is called wingsurfing and is performed on flat open spaces such as beaches or fields. Utilizing the wind, riders can achieve incredible air time and perform tricks that would otherwise require a massive ramp. It is even possible to ride uphill with sufficient wind. Unlike powerkiting with a mountain board, the Dirtsurfer is unidirectional; that is, it only goes one direction. However, it is possible, using the power of a kite or kitewing, to tack and gybe, much like a boat or windsurfer to change direction. Unlike a windsurfer however, it is not practical to change sides when coming to the end of a run in one direction. To overcome this, most riders can make the transition from "heel-side" to "toe-side". Riding toe-side means that your toes not your heels, point towards the floor as you lean forward into the wind, with your kitewing or kite behind you. This is not as difficult as it sounds. Due to the gyroscopic stability of the Dirtsurfer, speed is limited only by the wind, with recorded speeds well over 40 mph on a flat surface.
Information taken from wikipedia, read the full article.