The 2012 Paralympics in London involves 20 sports but not all disability categories can compete in each event.
Each sport has different physical demands and so has its own set of classifications.
Archery is open to athletes with a physical disability and classification is broken up into three classes:
Wheelchair users with impairment in all four limbs.
Wheelchair users with full arm function.
Athletes who compete in a standing position and also those who need to use a stool for support because of poor balance.
All disability groups can compete in athletics but a system of letters and numbers is used to distinguish between them.
A letter F is for field athletes, T represents those who compete on the track, and the number shown refers to their disability.
Track and field athletes who are visually impaired. Blind athletes compete in class 11 and are blindfolded and run with a guide runner. Athletes in class 12 are visually impaired but may choose to run with a guide.
Track and field athletes who are intellectually disabled. There are three events for men and women in the London programme - 1500m, long jump and shot put.
Track and field athletes with cerebral palsy or other conditions that affect muscle co-ordination and control. Athletes in class 31-34 compete in a seated position; athletes in class 35-38 compete standing.
Track and field athletes with short stature (dwarfism).
Track and field amputees. In class 42-44 the legs are affected and in class 45-46 the arms are affected. Athletes in these classes compete standing and do not use a wheelchair
Wheelchair track athletes. Athletes in class 51-53 are affected in both lower and upper limbs while T54 athletes have partial trunk and leg functions
Wheelchair field athletes. Athletes in F51-54 classes have limited shoulder, arm and hand functions and no trunk or leg function while F54 athletes have normal function in their arms and hands. In the F55-58 classes the trunk and leg function increases.
Boccia (a bowling game) is open to athletes with cerebral palsy and other severe physical disabilities (eg muscular dystrophy) who compete from a wheelchair, with classification split into four classes.
Players with cerebral palsy who are able to use their hands or feet to consistently propel a ball into play. BC1 athletes may have an aide on court to pass them their ball before each shot.
Players with cerebral palsy who are able to use their hands to consistently propel a ball into play and have greater functional ability than a BC1 athlete.
Players with cerebral palsy or other disability with locomotor dysfunction in all four limbs who are unable to throw or kick a ball into play and as such are permitted to use an assistive device such as a ramp to propel the ball into play and are supported by an assistant ("ramper") who adjusts the ramp on the instructions of the player.
Players who do not have cerebral palsy but have another disability with locomotor dysfunction in all four limbs and have similar functional ability to BC2 athletes. Conditions such as muscular dystrophy, spina bifida and tetraplegia will fall under this classification.
Cycling is open to amputees, "les autres" (athletes whose disability does not fall under one of the other categories), athletes with cerebral palsy and visually impaired athletes, competing in individual road race and track events.
Athletes with physical impairments either compete on bicycles (road and track), handcycles or tricycles (road only).
Visually impaired athletes compete on tandems with a sighted guide.
Handcycle sport classes H1-4:
Cyclists in H1-3 compete in a reclined position. H1 athletes have no trunk or leg function and limited arm function while H3 athletes have no leg function but good trunk and arm function. H4 athletes sit on their knees and use their arms and trunk.
Races for athletes who are unable to ride a bicycle because of a condition affecting their balance and co-ordination. Athletes in the T1 class have more serious co-ordination problems then T2 athletes.
Cyclists may have a condition like cerebral palsy or have a leg or arm amputation. C1 athletes have the most severe limitation while C5 athletes meet the minimum disability criteria.
All disability groups can take part in equestrian sport with Para-dressage the only event on the Paralympic programme.
Riders are divided into five grades.
Severely disabled riders with impairments of all limbs and poor trunk control who usually use a wheelchair in daily life.
Riders with either severely reduced trunk control and minimal upper limb conditions or moderate upper and lower limb and trunk conditions. Most use a wheelchair in daily life.
Riders have a very limited ability in both lower limbs and a good trunk balance, or milder limitations in upper and lower limbs with reduced trunk control. Some use a wheelchair in daily life.
Ambulant riders (those able to walk independently) who have impairments in both arms or have no arms, or moderate impairments of all four limbs. This category also includes blind riders and those with conditions such as dwarfism.
Ambulant athletes with either impaired vision or reduced motion or muscle strength or impaired arm or leg function.
Five-a-side football is played by those with a visual impairment, while seven-a-side football is played by athletes with cerebral palsy.
All players in the five-a-side game must wear eyeshades except the goalkeeper, who is sighted but cannot leave the area. There are no offside rules.
The football contains ball bearings to produce a noise when it moves.
Seven-a-side football consists of players from the C5, C6, C7 and C8 divisions, rated according to limb control and co-ordination problems when running.
All classes are comprised of ambulant athletes. Those in class five are least physically able; those in class eight are minimally affected.
At least one C5 or C6 class athlete must be on the field at all times and a team is not allowed to have more than two C8 players on the field.
Goalball is played by visually impaired athletes and a special rule means there is no need for classification.
Participants wear black-out masks to ensure everyone, whether blind or visually impaired, competes equally. The masks are checked during the game.
The ball has bells inside it to help to orientate the players and, as a result, the game is played in total silence.
Judo is contested by visually impaired athletes only. There is no categorisation as competitors are divided by weight in the same way as able-bodied athletes.
The main difference is that athletes begin the bout "gripped up" (holding each other) rather than apart.
Powerlifting is open to all athletes with a physical disability and is classified by weight alone.
Powerlifters competing at the Paralympics have disabilities in their lower limbs or hips, including paralysis, cerebral palsy and lower limb amputation.
Both male and female competitors take part in 10 weight classes.
Rowing is divided into four boat classes.
A fixed-seat single scull boat for men. Athletes have full movement in their arms only.
A fixed-seat single scull boat for women. Athletes have full movement in their arms only.
A two-person, mixed-gender scull for athletes with trunk and arm movement only.
A two-male and two-female boat, plus cox with sliding seats. Open to athletes with an impairment but who have movement in the legs, trunk and arms. A boat can include a maximum of two visually impaired athletes who wear blindfolds during training and competition.
Sailing is a multi-disability sport where athletes from the amputee, cerebral palsy, visually impaired, wheelchair and les autres groups can compete together.
There are three sailing classes: the
which is a mixed three-person crew, the
a mixed two-person class, and the
event, which is single-crewed.
Competitors are ranked according to a points system from one to seven, where low points are given to the severely disabled and high points for the less disabled.
Each crew of three is allowed a maximum of 14 points between them.
In the Skud-18 category, one sailor has a more severe level of disability (equivalent to a class one or two) while the other must have a minimum level of disability that prevents them competing on equal terms with able-bodied sailors.
Single-handed sailors must have that same minimum level of disability.
Shooters are divided into wheelchair and standing groups.
These divisions are split into six sub-classes, each of which determines the type of mobility equipment the competitor is allowed to use.
For pistol and rifle competitors who do not require a shooting stand.
For rifle competitors who have an upper limb disability and require a shooting stand.
Swimming is the only sport that combines the conditions of limb loss, cerebral palsy (co-ordination and movement restrictions), spinal cord injury (weakness or paralysis involving any combination of the limbs) and other disabilities (such as dwarfism and major joint restriction conditions) across classes.
Allocated to swimmers with a physical disability. The lower the number, the more severe the disability.
Allocated to swimmers with a visual impairment.
Allocated to swimmers with an intellectual disability.
denotes the class for freestyle, backstroke and butterfly.
denotes the class for breaststroke, and
denotes the class for individual medley.
The prefix and class number provide a range of classifications, from swimmers with severe disability (S1, SB1, SM1) to those with minimal disability (S10, SB9, SM10).
In any one class, swimmers may start with a dive or already in the water. This is taken into account when classifying an athlete.
Swimmers may have a classification that varies according to their event - for example, it may change between breaststroke and backstroke, according to the effect of their disability on the event in question.
Class 14 returns to the Paralympic Games in London after being omitted in Athens and Beijing.
Table tennis is played by athletes with a physical or intellectual disability divided into 11 classes.
Athletes competing from a wheelchair, with class one the most severely disabled and class five the least disabled.
Ambulant athletes, with class six the most severely disabled and class 10 the least.
Athletes with an intellectual disability.
Sitting volleyball is contested by athletes with a physical disability with Britain competing for the first time in the sport in London in the men's and women's competitions.
There are two classes called Minimally Disabled (MD) and Disabled (D) and a team may only have one MD player on the court while the other five players have to be class D.
Basketball is open to wheelchair athletes, whose impairments may include paraplegia, lower limb amputation, cerebral palsy and polio.
Athletes are classified according to physical ability and are given a points rating between one and 4.5. One point equates to the most severe disability, 4.5 to the least.
Each team fields five players but may not exceed a total of 14 points at any time.
Fencing is open to wheelchair athletes, whose impairments may include spinal cord injuries, lower limb amputation and cerebral palsy and whose conditions prohibit them from competing against standing, able-bodied fencers.
Athletes competing in this event are split into two classes.
Athletes with good balance and recovery, and full trunk movement.
Athletes with poor balance and recovery, but full use of one or both upper limbs.
Wheelchair rugby athletes are classified using a points system, with the most severely disabled athletes being graded at 0.5 points, rising to 3.5 points for the more able.
Each team is comprised of four players and is allowed a maximum of eight points on court at any one time.
Tennis is played from a wheelchair with two classes - open and quad (disability in three or more limbs).
In wheelchair tennis competitions, players are allowed two bounces of the ball, the first bounce being within the bounds of the court.