Bike suspension refers to the system that absorbs shocks and bumps while riding, enhancing comfort and control. It typically consists of components like forks in the front and a rear shock in the back, which work together to smooth out the ride over rough terrain. There are two main types of bike suspension: hardtail and full-suspension. Hardtail bikes have a suspension fork in the front but no rear suspension, making them lighter and more efficient on smooth trails. Full-suspension bikes have both front and rear suspension, providing better traction and comfort on uneven surfaces.