Producing only what is needed, when it is needed, in the amount needed. The opposite of batch-and-queue production. kiichiro-toyoda first articulated the JIT vision for Toyota, but it was taiichi-ohno who spent decades making it operationally real. JIT requires pull-production (triggered by downstream demand, not upstream schedules), heijunka (leveled production to smooth demand variation), small lot sizes enabled by smed, and reliable processes enabled by jidoka. The kanban system is the signaling mechanism that makes JIT work. JIT was validated dramatically during the 1973 oil crisis, when Toyota's lean inventory system proved far more resilient than competitors' batch operations. Described in toyota-production-system-beyond-large-scale-production and the TPS Basic Handbook. For a comprehensive inventory of TPS-related online resources and primary source materials, see tps-works-online-inventory.