The term Universal Design was coined by the late Ronald L. Mace, an architect with a disability who was the founder and former program director of The Center for Universal Design at North Carolina State University. In his words, Universal Design calls for "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.”
The Seven Principles of Universal Design as applied to architecture, environmental, and product design address:
equitable use, flexibility in use, simple and intuitive use, perceptible information, tolerance for error, low physical effort, size and space in approach and use
You can find information about each of these principles at the Institute for Human Centered Design.
Universal Design considers the variability of humans which includes diverse physical, perceptual, cognitive abilities, and the wide variety of body shapes and sized. With all this in mine, products and environments can be more functional and user-friendly for everyone.
The Americans with Disabilities Act (ADA) functions to protect the civil rights of people with disabilities by ensuring that they are not unfairly denied access to job opportunities, goods or services due to their disability. This includes the 2010 ADA Standards for Accessible Design. This legislation and the accompanying standards present the bare minimum that is required to prevent discrimination against people with disabilities. Universal Design goes far beyond this to provide best practices for design with everyone's needs in mind.
For the last two decades, educators have expanded the principles of UD to the field of education. The work of educational researchers Shaw, Scott, and McGuire at the University of Connecticut led to the development of nine principles for the implementation of Universal Design for Instruction (UDI). These principles utilized the Seven Principles of UD applied to an educational setting and added two principles for consideration in instructional design: the community of learners and the instructional climate.