For as long as there has been Bicycles people have been riding and racing them off road. However, factory produced purpose built off-road bicycles have only been around since 1981.
Most commonly known by the name "mountain bike" these bicycles have burly frames, fat knobbly tyres, durable components and often forms of suspension. The inherent comfort and flexibility of the modern mountain bike has led to an estimated 80% market share in western countries like the US, UK, Canada, Australia, and New Zealand.
While it is estimated only 10-20% of mountain bikes are actually ridden off-road the sport of mountain biking has seen an explosion in popularity, and diversification.
Sub-categories of mountain biking include:
Offroad/Downhilling - Gravity assisted racing on specialized mountain bikes with long travel suspension and powerful brakes.
Offroad/Epic_Riding - All day or multiday adventures in remote wilderness areas.
Offroad/Dual_Slalom - Head to head racing along purpose built courses.
Offroad/Trials - Slow negotiation of obstacles (purpose built and natural) with out touching the ground.
Offroad/Urban_Scuttling - Pedestrian irritating jump/trick riding through urban centres.
Offroad/Night_Riding - Using battery powered headlights to ride off-road during the hours of darkness.