With the recent developments in robotics, mobile robots are gaining momentum and are increasingly involved in our lives. Robot exploration and mapping are essential tasks for robot navigation in unknown environments. In the last three decades the challenge has grown and many researches have tried to accomplish these tasks through a team of robots. The use of multi-robot systems represents a big challenge because they require robots able to collaborate each other and, then, to create coordination techniques to make the multi robot system efficient. Multi-robot mapping introduces many advantages, providing a faster and efficient map building even in high dimensional unknown environments.