By now, you or one of your friends probably owns a three-armed toy called a fidget spinner. It seems like almost every kid has one, but how did they become so popular? The toy was originally designed to help children with ADHD (Attention Deficit Hyperactivity Disorder) stay relaxed and focused. As soon as others saw the toys, children all over the world wanted one. They shared and talked about them on social media websites, like Facebook, YouTube and Instagram.