Introduction to Accessibility

What is accessibility

An accessible product or service is one which can be used by all its intended users, taking into account their differing capabilities. A user's ability to make inputs and perceive outputs may be impaired. This can be either permanent or temporary and may be due to various physical, mental or environmental conditions. Consider the following quote from a bank customer, trying to use the bank cash dispenser:

"At night I can see the writing, but by day I find it impossible to use. I know there's something written there but I don't know exactly what it says."

Take steps to reduce glare


Ensure that when the device is installed the screen is visible those both seated and standing.

This quote comes from a user who is partially sighted. Being partially sighted is one cause of impairment for this user. This makes it difficult for her to read text when it is small or when the colour of the text does not contrast well with the background colour. Trying to use the terminal in bright daylight is a second cause of impairment. Sunlight reflecting off the display reduces the contrast even further. The result is that during the day, the combination of poor sight and reflected light makes it impossible for this user to access the terminal.

Impairments affect the user's ability to perceive, understand or physically manipulate things. They can occur for many different reasons, including medical conditions, injury, the environment or simply old age.

For example, users may have difficulty perceiving visual things if they are blind or partially sighted, if they have lost or forgotten their glasses or if they are working in a dark or very bright environment. They may have difficulty perceiving sounds if they are deaf or hard of hearing or if they are working in a noisy environment.

Users may have difficulty understanding things if they have a learning impairment, if they are tired or stressed or if they have a low level of literacy in the language used.

Users may have difficulty manipulating things if they have a physical disability, an injury or simply if they are getting older.

Users may also be impaired by the technology itself. For example, services that are delivered through websites require users to provide their own technology in the form of computer hardware, operating system and Web browser software. If these are old or slow, they may not have the capability to interpret or display what is on the Web page.

How do accessibility barriers arise?

Accessibility barriers occur when the design of the technology fails to allow for the variations in users' abilities. This can be as simple as failing to shield a cash dispenser display from sunlight. Or it could be something more fundamental to the design, such as a poor choice for the colour and size of buttons:

"The keys are grey and the numbers on the keys are black, so it's hard to read. Also, the keys are very close together so it's difficult to see one from the other."

These problems can be avoided by appropriate design. Design which takes into account the abilities of all users and the conditions of use.

Control Difficulties

guidelines_img_two_finger_mousing (1)

Many users find normal controls difficult to use. This image shows a person using two hands to operate a standard mouse.

Provide a clear access path

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Ensure easy access to the device for people using wheelchairs, buggies or mobility aids.

Alternative methods of interaction


Many people use a pointing device but cannot use a keyboard.

Accessibility goals

A service delivered through information technology will be accessible to the widest possible audience if the following conditions are met:

  • All users are able to perceive and understand the controls, instructions and outputs
  • All users are able to reach and manipulate the controls, inputs and outputs
  • The user interface is consistent across functions, devices and repeated use
  • For users who still cannot use the service, an equivalent alternative service is available

The controls, instructions, inputs and outputs might include such things as buttons and keys, the labels that indicate their function, identification cards, menus and prompts, displayed information, delivered outputs such as money or tickets, audible warning beeps and indicator lights.

Who benefits from accessibility?

Increased accessibility brings benefits for users, producers, service providers and society at large.

  • Users benefit from being able to use the product or service more effectively, increased independence, inclusion in society and better employment prospects.
  • Producers benefit from compliance with the purchasing requirements of public and corporate customers, additional selling points for end users and kudos.
  • Service providers benefit from maximising the number of customers and reducing the need to provide expensive alternative channels for customers who do not have access.
  • Society at large benefits through the inclusion of more citizens in the democratic process, increased numbers in the workforce and less spending of public money on care services.

Accessibility is inclusive. By focussing on the needs and abilities of all users in all situations, it aims to include more of the users more of the time. Other terms for accessibility are Inclusive Design, Universal Design and Design for All.

Guidelines for making products and services accessible