The main Paralympic categories are based on visual impairment, amputations, cerebral palsy, spinal and other disabilities (wheelchair category) and intellectual disabilities.

The visual impairment category is for people who have been declared legally blind after a medical test, which isn't always the same as completely blind.

The amputee category is for people who have lost one or more of their limbs.

The wheelchair category may include amputees and people with cerebral palsy, depending on the level of impairment. The rule is that there has been at least a 10% loss of function in the lower limbs.

Intellectual disability is usually measured by IQ, which should be below 70, and whether the athlete is unable to fulfil certain functions.

There was also an 'other' category, but this has now been merged into the other main categories. You can find more exact information on the Paralympic categories here.