A terrain park or snow park is an outdoor recreation area containing terrain that allows skiers, snowboarders and snowbikers to perform tricks. Terrain parks have their roots in skateparks and many of the features are common to both.

From their inception to as recently as the 1980s, ski areas generally banned jumping and any kind of aerial maneuvers, usually under penalty of revoking the offender's lift ticket. By the 1990s, most areas provided snow features specifically catering to aerial snowsports. One of the first in-bounds terrain parks was the snowboard park built in 1990 at Vail's (Colorado) resort. The park was copied soon in other resorts. Today most resorts have terrain parks, with many having multiple parks of various difficulty. Some resorts are almost exclusively terrain parks such as Echo Mountain Park in Evergreen, Colorado and Snow Park in Wānaka, New Zealand. In Colorado there has been a recent trend for defunct resorts such as Squaw Pass (now Echo Mountain Park) to be reopened, catering to terrain park users.

The first known terrain park (then called a ‘snowboard park’) was built at Bear Valley Ski Area (California) in the 1989–90 season. It was the brainchild of Bear Valley's Marketing Director Sean McMahon and California snowboarder and contest organizer Mike McDaniel.

McMahon's idea was to create an area of the mountain specifically for snowboarders—modeled after the skateparks of the 1970s, featuring jumps, jibs, and a halfpipe—that would bring new customers to the small, family operated ski area in the Central Sierra. He enlisted the help of McDaniel, who had experience building snowboard-specific terrain features such as halfpipes and jumps, through his work organizing early snowboard events. McDaniel in turn, brought in snowboard pioneers Mike Chantry and Keith Kimmel to consult on the design and construction of the park, to be located on the front side of Bear Valley's upper mountain.

A surface lift was installed to bring snowboarders from the bottom of the area back to the top, without having to take a chair lift to the top of the mountain. Kim Krause, who had run lifts in other areas of the resort, was brought on as the park's first lift operator.

It became apparent that the park would need ongoing construction, grooming, and maintenance, and McDaniel was hired by Bear Valley in the fall of 1989 to be Snowboard Park Manager. The new mountain attraction was dubbed the “Polar Park.” Opening day in late November 1989 featured a demonstration by professional snowboarders Damian Sanders, Terry Kidwell, Noah Salasnek, Mike and Tina Basich and others. The event was covered by Thrasher Magazine, International Snowboard Magazine and local media.

Terrain parks (in the United States and Canada) have designations with respect to safety similar to standard alpine slopes. They differ in their designation and degrees of difficulty. They are identified with orange ovals to differentiate them from standard slopes, and are further distinguished by large, medium, or small features. While features vary between resorts, commonly small features are short jumps and rails that are at the slope surface, Medium features are 10-to-30-foot (3.0 to 9.1 m) high jumps along with jibs requiring small jumps to mount. Large features include 30-to-90-foot (9.1 to 27.4 m) jumps along with complex jibs and large vertical pipes.

"Progression parks" are easier terrain parks, meant for those just starting to ride these features.