My beginner bodyweight program–pushup, pullup, squat and L-sit, along with walking and running–technically require only one piece of equipment. You need a pullup bar to raise your weight off the ground. And if you’re outside, you should probably wear shorts..and a top if you’re a lady. 🙂
As you get further into the bodyweight world, you’re going to want to expand your repertoire. Thanks to the Navy SEALs, we now have a way to develop the body in multiple dimensions simultaneously using suspension training: TRX.