- Universal design (UD) in architecture aims to make buildings and environments accessible to all by removing barriers rather than designing for the average user. - UDL applies these UD principles to education by ensuring the learning environment (curriculum, materials, teaching) is accessible and beneficial to all students by considering diversity from the start of lesson planning rather than retrofitting afterwards. - The UDL Guidelines provide a framework to help apply the three UDL principles of engagement, representation, and action and expression to educational practice through multiple means of representation, engagement, and expression.