According to the Disability Discrimination Act (DDA) 1995, a disability is a physical or mental impairment that has a long-term or substantial effect on a person's ability to carry out day to day tasks.
This ranges from people with physical and sensory impairments to people with diabetes, disfigurements, heart disease and epilepsy. Not all of these conditions affect how an individual may use software.
Eyesight
This includes people with no vision, or some functional vision. For example, screen readers are used by blind and partially sighted people to read what appears on a computer monitor. Someone with low vision may use screen magnification software or adjust their display settings to make reading more comfortable.
This group also includes people with colour blindness and those with sight problems related to ageing.
Hearing
This includes people who are completely deaf or have partial hearing in one or both ears and require the use of a hearing aid.
Mobility
This refers to a wide range of people with varying types of physical disabilities. With regards to the use of software, it refers largely to people with reduced upper limb mobility or manual dexterity, and co-ordination problems. This can be caused though a disability that an individual is born with, or one that develops due to illness, such as Multiple Sclerosis (MS), Parkinson's disease, or a stroke. People with a broken bone would also temporarily fall into the category.
Cognitive
Cognitive impairment refers to people with dyslexia and learning difficulties. Dyslexia is a condition where people have difficulties with reading, writing or spelling. Learning problems can range from someone who has a serious mental impairment, or may be due to more common factors. These may be poor literacy, a low level of skill using a computer, having to use software in a second language, or problems understanding information.
Further information
Find out more about the definition of disability under the DDA.
Learn about the web accessibility myths.
Further information about IT and accessibility.