Bodyweight exercises only require your own body weight to workout with. Your weight provides resistance for all the movements that you do. Bodyweight exercises build lean muscle, give your body endurance, flexibility and strengthen your body from its core. Bodyweight training can lead to stronger bones and a stronger immune system. Bodyweight exercises are convenient because you can work out anywhere; your home, at work, on vacation, at a park, the beach, pick your place.
These exercises can be for people of all fitness levels and the degrees of difficulty can be adjusted by simply modifying your position. Some bodyweight exercises that you may be familiar with are pushups, crunches, dips, the plank, chin ups, squats and yoga, to name a few. There are also bodyweight exercises that provide cardio workouts as well such as jumping rope, jumping jacks, swimming, and jogging.
Using your own bodyweight to exercise with does not cost a dime. You do not have to go anywhere to do any of these exercises (unless you want to). However, no one can do the exercises for you, you have to put the effort in to do it, just like anything else. Get to it and report your results in the comments below.