First In, First Out - FIFO

What Does First In, First Out - FIFO Mean?
An asset-management and valuation method in which the assets produced or acquired first are sold, used or disposed of first. FIFO may be used by a individual or a corporation.

Investopedia explains First In, First Out - FIFO
For taxation purposes, FIFO assumes that the assets that are remaining in inventory are matched to the assets that are most recently purchased or produced. Because of this assumption, there are a number of tax minimization strategies associated with using the FIFO asset-management and valuation method.