Paralympic swimming is split up into categories. The first is the race for the visually impaired swimmers. They use people called "tappers" who use a long pole to tap the swimmers back to indicate when they should turn. The second category is for people with physical disabilities who (depending on whats wrong) have to swim with just their arms or legs. The third category is for people with dwarfism and disabilities which affect there joints. The final category is for people who suffer with mental disabilities.
A bit of History
The swimming pool is 50m long, 25m wide and three metres deep. It is divided into 10 lanes, although only the centre eight lanes are used for the Games. Swimming is one of the few sports that has been featured in every Paralympic games. It is one of the most popular Paralympic sports. There are four strokes that you can enter in the Paralympics Freestyle, Back Stroke, Breaststroke and Butterfly.
Whilst the start for all swimmers is vital, a false start will result in disqualification. Judges will also be looking closely that stroke and turning techniques are legal and that in the relay events each swimmer touches the end of the pool before their teammate leaves the starting podium, side or wall.