Swimming was included in the first modern Olympic Games in Athens in 1896. Global rules for swimming competitions require respecting the starting order, completing the required distance for each event, and using times for classification. Important competitions include the 2016 South American Swimming Championship in Paraguay. Equipment for swimming includes swimsuits, flip flops, towels, caps, and goggles. Some of the most important swimmers are Michael Phelps, Alexander Popov, and Mark Spitz. There are four main styles of swimming: crawl, breaststroke, butterfly, and backstroke.