American fast-casual chain founded in 1993 by Steve Ells, famous for the "Food with Integrity" positioning and a tightly engineered assembly-line operating model. Frequently cited as a case study in unit economics, throughput per store, and how a strong operating system compounds — until the 2015 E. coli crisis showed how brittle food-safety reputation can be. Relevant for founders as a lesson in operational tightness and how a single quality failure can erase years of brand equity.