Spin classes are group fitness sessions that focus on indoor cycling. Participants ride stationary bikes while following an instructor who leads them through various workouts, often set to music. The intensity can vary, allowing individuals to adjust their resistance and speed according to their fitness levels. These classes typically last 45 to 60 minutes and include a warm-up, a series of cycling drills, and a cool-down. Spin classes are popular for their ability to provide a high-energy workout that improves cardiovascular fitness, builds strength, and burns calories in a fun, motivating environment.