First-In-First-Out (FIFO) is an inventory management method where the oldest stock is sold or used first. This approach helps businesses manage their inventory efficiently, ensuring that products do not expire or become obsolete. FIFO is commonly used in industries like food and pharmaceuticals, where freshness is crucial. In a FIFO system, items are organized so that the first ones added to inventory are the first ones to be removed. This method can also apply to data structures in computer science, where the first data entered is the first to be processed, ensuring orderly and predictable operations.