Final answer:
The FIFO rule means older stock is used before new stock to ensure freshness and minimize waste.
Step-by-step explanation:
The first in, first out (FIFO) rule in the context of food storage and organization means that older stock is used before new stock. This method helps to ensure that food is consumed while it's fresh and reduces waste by minimizing the chance of food expiring before it is used. It’s an efficient way to organize inventory and is frequently used in both home pantries and professional kitchens.