The concepts, advantages and disadvantages of periodic inventory system and perpetual inventory system and their scope of application.

1) periodic inventory system is also called "periodic inventory system". It refers to an inventory accounting method in which only the increase of inventory is registered in the relevant account books, but not the decrease, according to accounting vouchers. At the end of the month, the actual inventory quantity is taken as the book balance, and then the quantity issued in this period is calculated reversely. The advantage of periodic inventory system is that it can simplify daily accounting work. There are two main disadvantages: first, the increase and decrease of various inventories and balances cannot be reflected and monitored at any time through account books; Second, the cost from sales to extrusion may not conform to the actual situation, and may contain some losses or errors, which is not conducive to the control of inventory by account books, the strengthening of inventory management and the protection of property safety. Therefore, the periodic inventory system is generally only applicable to some materials with low value, miscellaneous varieties and frequent access. The periodic inventory system is generally not applicable to other inventories. 2) perpetual inventory system, also known as the book inventory system, is an inventory accounting method to calculate the book balance of ending inventory according to account book records. Using this method, the increase and decrease of inventory should be recorded continuously in the account book at ordinary times, and the book balance should be calculated at any time. The advantage of perpetual inventory system is that it can know the income, delivery and balance of inventory at any time, which is conducive to strengthening inventory management. The disadvantage is that it increases the daily accounting workload. Therefore, in practical work, except for a few special cases, perpetual inventory system should generally be adopted.