First world, second world, and third world

The first world has the best weapons, political system, and social system. They have advanced education. In the second  world, everything is under the country's control, but the government left some respect for their people in a certain field. In the third world, I do not know much about the third world. I think it is a big problem because not many people know it. Therefore, people should put more attention on the third world. Nowadays,  a phenomenon is the economic in the third world is not stable.