The concept originated in physical architecture, most famously through curb cuts, which were built for wheelchair users but ended up helping parents with strollers, delivery workers, and cyclists too. Applied to digital products, universal design pushes teams to build one flexible experience that works for the widest range of people and situations, rather than a separate “accessible version” bolted on afterward.
It’s closely related to inclusive design but originates from physical product and environmental design rather than software specifically.