FIFO assumes older stock expires first, but that is not always true. A batch of yoghurt delivered today might carry a shorter shelf life than one delivered yesterday, or a vaccine lot received later may expire sooner. First Expired, First Out uses the expiry date as the deciding factor, so the shortest-dated stock always moves first.
FEFO is standard practice in pharmaceutical storage and distribution, and increasingly in retail dairy, chilled ready meals and packaged foods. It needs good labelling and discipline: expiry dates must be visible when the product is on the shelf, and staff or the stock system must check them when picking. In a display cooler, placing shortest-dated stock at the front is FEFO in action.
A pharmacy in Lucknow storing insulin pens in a refrigerator might arrange them by expiry date, not by delivery date, and check the order each time a new batch arrives. A dairy section in a supermarket follows the same logic when it pulls short-dated milk to the front.