Mountain bikes, also known as MTBs, are specifically designed for off-road cycling, incorporating features that enhance durability and performance on rough terrains. These bikes are characterized by their robust construction, which includes suspension forks, large knobby tires, durable wheels, powerful brakes, and wide handlebars for improved balance and comfort. Additionally, many mountain bikes feature rear suspension systems and dropper seat posts that allow riders to quickly adjust seat height for optimal pedaling and maneuvering.

Originally developed for mountain trails, single tracks, fire roads, and other unpaved surfaces, mountain bikes are also popular on paved surfaces due to their upright riding position, comfortable ride, and stability. The terrain commonly encountered in mountain biking includes rocks, roots, loose dirt, and steep grades. Many trails are enhanced with technical trail features (TTFs) like log piles, rock gardens, gap jumps, and wall-rides, which these bikes are built to handle. The sturdy construction and wider tires make mountain bikes suitable for urban riders and couriers navigating potholes and curbs.

Since the sport of mountain biking emerged in the 1970s, it has diversified into various subtypes such as cross-country (XC), enduro, all-mountain, freeride, downhill, and slalom. Each subtype places different demands on the bike, leading to specialized designs for optimal performance. Innovations in mountain bike technology have led to increased suspension travel, now often up to 8 inches (200 mm), and advanced gearing systems, including the popular "1x" drivetrains with a single chainring in the front and a wide-range cassette at the rear. This simplifies gear selection and reduces weight while providing versatility for both climbing and descending.

Although terms like "all terrain bicycle" (ATB) are sometimes used interchangeably with mountain bike, they are considered outdated by some. Regardless of the terminology, mountain bikes continue to be the preferred choice for adventurers seeking to tackle diverse and challenging terrains.