Several terms have emerged in recent years that describe similar though somewhat distinct design concepts. The terms accessible design, usable design, and universal design are all approaches to design that can result in products that are easier for everyone to use, including people with disabilities. These concepts apply to design of the built environment, of customer services, and the other products and environments, including information technologies such as hardware, software, multimedia, distance learning courses, websites, curriculum, and instruction.
Accessible design is a design process in which the needs of people with disabilities are specifically considered. Accessibility sometimes refers to the characteristic that products, services, and facilities can be independently used by people with a variety of disabilities. Accessibility as a design concern has a long history, but public awareness about accessibility increased with the passage of legislation such as the Americans with Disabilities Act (ADA) , which mandated that public facilities and services be fully accessible to people with disabilities.
In 1998 an amendment to Section 508  of the Rehabilitation Act of 1973 was passed. The amendment mandated that the Access Board  develop accessibility standards for software, hardware, websites, videos, and other information technology. Although these standards apply directly to the development, procurement, modification, and use of information technology of U.S. federal agencies, many states, educational institutions, and other entities have adopted them as one way to meet their ADA obligations. The Web Accessibility Initiative  of the World Wide Web Consortium has also developed guidelines and comprehensive resources for designing accessible web pages.
Universal design is a broader concept that is defined by The Center for Universal Design  at North Carolina State University as "the design of products and environments to be usable by all people, to the greatest extent possible, without the need for adaptation or specialized design."
Sidewalks with curb cuts and doors that automatically open when a person moves near them are examples of universally designed products. They benefit people with disabilities, parents with baby strollers, delivery workers, and others. Human characteristics considered in universal designs may include age, gender, stature, race/ethnicity, culture, native language and learning preference.
In the case of information technology, products that are universally designed are accessible to and usable by people with a wide variety of characteristics, including different types of disabilities. These products are often designed to eliminate or minimize the need for assistive technologies. At the same time, they are compatible with common assistive hardware and software devices. For more information about applications of universal design, consult DO-IT's Applications of Universal Design .
Both accessible and universal design are concerned with addressing the needs of users beyond those considered to be "average" or "typical."
Like accessible and universal design, usable design serves to create products that are easy and efficient to use. Usability has been defined by the International Organization for Standardization  as the "effectiveness, efficiency, and satisfaction with which a specified set of users can achieve a specified set of tasks in a particular environment." Usability engineers test the ease at which users can learn to operate a product and remember how to do so when they return to the product at a later time.
Unfortunately, people with disabilities are not always included in usability tests. Therefore, many products that perform well in usability tests are not accessible to people with disabilities. Increasingly, accessible and universal design considerations are being addressed by usability professionals. For example, accessibility is now a topic on high-profile usability websites such as Usability.gov  and Usability First .
Usability shares some key goals with accessibility and universal design. Designers in all three disciplines seek to create product features that are easily discovered and operated by the user. Usability engineers are concerned with aspects of the user experience, that include:
- Learnability: Can users easily learn how to operate the product, and can they remember how to perform tasks when they return to the product the next time?
- Consistency: Are product features clearly and consistently labeled?
- Efficiency and effectiveness: Can users perform tasks with a minimal amount of effort and achieve their goals successfully?
If product designers apply universal design principles, with a special focus on accessibility for people with disabilities, and if usability experts routinely include people with a variety of disabilities in usability tests, more products will be accessible to and usable by everyone.
-  Americans with Disabilities Act (ADA)
-  Section 508
-  Access Board
-  Web Accessibility Initiative
-  The Center for Universal Design
-  Applications of Universal Design
-  International Organization for Standardization
-  Usability.gov
-  Usability First