Resistance training, also known as strength training or weightlifting, is a type of physical exercise that involves using resistance to build muscle strength and endurance. This can be achieved through various methods such as lifting weights, performing bodyweight exercises like push-ups or pull-ups, or using equipment like resistance bands or machines. The goal of resistance training is to gradually increase the amount of weight being lifted or the level of difficulty in an exercise in order to continuously challenge and build muscle strength. It's a great way to improve overall fitness, as well as prevent age-related muscle loss and maintain bone density.