cost of goods available for sale
Picture everything a shop could possibly have sold this period gathered in one place: the leftover stock it carried in from last month, plus every new box it bought this month. That whole pool — everything that was, at some point, available to be sold — is the cost of goods available for sale. The shop will not sell all of it; whatever it does not sell simply stays as ending inventory.
Numerically, cost of goods available for sale = beginning inventory + net purchases (purchases plus freight-in, minus purchase returns and discounts). It is the grand total of cost sitting in the business before you split it into two destinations. From this single pool, the period-end physical count tells you how much stayed (ending inventory), and the rest must have left as cost of goods sold. So: goods available for sale = ending inventory + cost of goods sold. If 25,000 was available and 6,000 is left, then 19,000 was sold.
It matters as the pivot of all inventory accounting: it is the number you split between the balance sheet (unsold goods) and the income statement (sold goods). Every cost-flow assumption — FIFO, LIFO, average — is really just a different rule for slicing this same pool into 'still here' and 'gone'. They never change the total available; they only change where the line is drawn between inventory and cost of goods sold.
A toy store starts with 5,000 of inventory and makes net purchases of 20,000, so cost of goods available for sale is 25,000. Whatever method it uses, that 25,000 splits into just two parts: ending inventory and cost of goods sold. Count 6,000 left, and 19,000 was the cost of goods sold.
The one pool that splits into ending inventory and cost of goods sold.
Cost-flow assumptions never change the total goods available for sale — they only decide how that fixed total is split between ending inventory and cost of goods sold.