One of the major features of any inventory system is that you can find out the value of any item based on its historic or average price. You can also find the value of all your items for your balance sheet. Why is valuation important?
You may encounter these terms, so lets clarify:
There are two major ways in which ERPNext values your items.
New Value X2 = (X * Y + X1 * Y1) / (Y + Y1)