The twin paradox is a great way to show what special relativity models and it's something that most people who want to understand it get stuck on. First it's important to understand basic Galilean relativity, all motion is relative. That just means that there's no distinction between object A moving away from object B and object B moving away from object A. Adding more objects for comparison makes no difference because an object at rest relative to one would in motion relative to the other. Special relativity is based on the speed of light being the same for all inertial (non accelerating) ob