A health club (also known as a fitness club, fitness center, health spa, weight room and commonly referred to as a gym) is a place that houses exercise equipment for the purpose of physical exercise.

In recent years, the number of fitness and health services have increased, expanding the interest among the population. Today, health clubs and fitness centers are a reference of health services, rising the adherence to physical activity.

Most health clubs have a main workout area, which primarily consists of free weights including dumbbells and barbells and the stands and benches used with these items and exercise machines, which use gears, cables and other mechanisms to guide the user's exercise. This area often includes mirrors so that exercisers can monitor and maintain correct posture during their workout. A gym that predominantly or exclusively consists of free weights (dumbbells and barbells), as opposed to exercise machines, is sometimes referred to as a black-iron gym, after the traditional color of weight plates.

A cardio theater or cardio area includes many types of cardiovascular training-related equipment such as rowing machines, stationary exercise bikes, elliptical trainers and treadmills. These areas often include a number of audio-visual displays, often TVs (either integrated into the equipment or placed on walls around the area itself) in order to keep exercisers entertained during long cardio workout sessions. Some gyms provide newspapers and magazines for users of the cardio theatre to read while working out.

Most 2010-era health clubs offer group exercise classes that are conducted by certified fitness instructors or trainers. Group exercise classes are often considered the most important service in the centers for members' engagement. Many types of group exercise classes exist, but generally these include classes based on aerobics, cycling (spinning), boxing or martial arts, high intensity training, step yoga, regular yoga and hot (Bikram) yoga, pilates, muscle training, stretching, and self-defense classes such as Krav Maga and Brazilian Jiu-Jitsu. Health clubs with swimming pools often offer aqua aerobics classes. The instructors often must gain certification in order to teach these classes and ensure participant safety.

Some health clubs offer sports facilities such as swimming pools, squash courts, indoor running tracks, ice rinks, or boxing areas. In some cases, additional fees are charged for the use of these facilities.

Most health clubs employ personal trainers who are accessible to members for training/fitness/nutrition/health advice and consultation. Personal trainers can devise a customized fitness routine, sometimes including a nutrition plan, to help clients achieve their goals. They can also monitor and train with members. More often than not, access to personal trainers involves an additional hourly fee.

Newer health clubs generally include health-shops selling equipment, snack/protein bars and smoothies, restaurants, child-care facilities, member lounges and cafes. Some clubs have a sauna, steam room, or swimming pool and even nutrition counseling. Health clubs generally charge a fee to allow visitors to use the equipment, courses, and other provided services. In the 2010s, some health clubs became eco-friendly (e.g., zero waste) and incorporated principles of "green living" in their fitness regimen.