Para-swimming classification is a function-based classification system designed to allow for fair competition in disability swimming. The classes are prefixed with "S" for freestyle, butterfly and backstroke events, "SB" for breaststroke and "SM" for individual medley events. Swimmers with physical disabilities are divided into ten classes based on their degree of functional disability: S1, S2, S3, S4, S5, S6, S7, S8, S9 and S10. The lower number indicates a greater degree of impairment. Those with visual impairments are placed in classes S11, S12 and S13. Class S15 is for athletes with hearing loss. Additional classes may be reserved for swimmers with intellectual impairment: S14,[1] S18 for swimmers with Down Syndrome or class-S14 intellectual impairment combined with a physical impairment,[2] and S19 for swimmers with autism.[3]
Swimming was one of the first organised sports for people with disabilities, and was contested at the first Summer Paralympics in 1960. Both the rules for the sport and approval of classifications were the responsibility of the Fédération International de Natation Amateur (FINA) until 1992, when the International Paralympic Committee took over the governance of classification. As of 2012, people with visual, physical and intellectual disabilities are eligible to compete in the sport. The classification system was originally based on medical criteria, but has since moved to one largely based on functional disability to make para-swimming more competitive. The sport is moving towards an evidence-based classification system.