Inline skating is a popular recreational activity where the skater glides on lightweight boots with three to five wheels attached in a line. Scott Olsen is the American entrepreneur credited with developing the first modern in-line skates as a way to train for ice hockey during the off-season. These skates were comprised of a metal frame, urethane wheels, and a heel brake. Olsen later founded Rollerblade, Inc., producing in-line skates for general recreation. The sport has evolved, and there are currently more than 30 in-line skating companies.

Skaters use a technique called striding, which is balancing on one foot while pushing off with the other. This is repeated with the opposite foot. To stop, skaters can use the heel brake (a rubber pad attached to the back of the skate), the t-stop (dragging one foot behind the body perpendicular to the other foot), or the powerslide (an abrupt turn).

Stunts and tricks such as grinding, curb launching, and vert skating are used by advanced skaters during aggressive skating, otherwise known as street skating. Grinding involves riding curbs, rails, and similar objects. Curb launches involve jumps off elevated surfaces. Vert skating is short for vertical skating and involves stunts in a half-pipe structure. Skate parks may have launch ramps and obstacles such as curbs, rails, and stairs for performing advanced tricks in an enclosed area. All riders, especially those performing these advanced stunts, should wear protective gear such as wrist and elbow pads, knee pads, and a helmet.

Most in-line skates weigh between 4 and 7 pounds. The boot is made of a hard plastic shell with laces and or buckles over a boot liner. On the bottom of each boot is a wheel frame housing three to five urethane wheels in vertical placement from heel to toe. Large wheels are more stable at high speeds, and they range from 76 to 80 mm in diameter. Smaller wheels allow for added maneuverability and measure from 70 to 72 mm in diameter.

Many skaters participate in in-line competitions, which include racing, aggressive skating, and roller hockey. In-line racing can be an individual or team pursuit, and is held on circuits from 1 to 50km in length. Skaters may compete in slalom runs, where two skaters race an obstacle course simultaneously. Most aggressive skating competitions are sponsored by the Aggressive Skater's Association; these competitions are held in skate parks around the world. Skaters compete in two 60 second or 90 second runs, combining moves on rails, ramps, and half pipes with free form skating tricks. Roller hockey rules are similar to those of ice hockey, with less physical contact. Roller hockey utilizes a ball instead of a puck. Amateur and professional roller hockey leagues have been overseen by Roller Hockey International and USA - Inline Hockey.