POUR is an acronym based on the principle that accessibility should be a priority when designing or purchasing material. Material should be Perceivable, Operable, Understandable, and Robust. While no two accessibility barriers are the same, POUR is an approach that takes all learners into account.
Perceivability means that the user can identify content using their available or preferred senses.
Operability means that a user can successfully use controls, buttons, navigation, and other necessary interactive elements.
Understandable technology is consistent in its presentation and format, predictable in its design and usage patterns, concise, multimodal, and appropriate to the audience in its voice and tone.
A robust design is standards - compliant, and designed to function on all appropriate technologies. Users should be able to choose the technology they use to interact with websites, online documents, multimedia, and other information formats.