All transactions concerning goods and services are linked by an accounting relationship between resources and uses. Over a period of time the total resources available for a product must necessarily be equal to the sum of its uses. For goods (and some services) changes in inventories allows us to adjust supply to demand over time.
The balance between resources and uses of a product is the following :
Production + imports + margins (trade and transportation) + taxes less subsidies on products = intermediate consumption + final consumption expenditure + gross fixed-capital formation + changes in inventories + acquisitions less disposals of valuables
Production and imports being estimated with basic price, margins (trade and transportation) and taxes less subsidies on products are necessary in order to obtain total resources with acquisition prices (the total supply).
Intermediate consumption, final consumption expenditure, gross fixed-capital formation, changes in inventories and acquisitions less disposals of valuables represent the total uses with acquisition prices (the total demand).