Perpetual Inventory Systems
Various types of perpetual inventory systems include manual, card-oriented, and computer- operated systems. In computer-operated systems, a programmed instruction referred to commonly as a trigger, automatically transmits an order to the appropriate vendor once supplies fall below a prescribed level.
The purpose of each of the three types of perpetual inventory approaches is to total up either the unit use or the value use (or both) of different items and product lines.
This information will serve to help avoid stockouts and to maintain a constant evaluation of the sales of different product lines to see where the emphasis should be placed for both selling and buying.
Periodic Inventory Systems
Periodic inventory is a system of inventory in which updates are made on a periodic basis. This differs from perpetual inventory systems, where updates are made as seen fit. In a periodic inventory system no effort is made to keep up-to-date records of either the inventory or the cost of goods sold.