The essence of futures is to sign long-term contracts with others to buy and sell commodities (or stock indexes, foreign exchange, interest rates).

Closing the position is equivalent to fulfilling the contract (lightening the position), and each hand closing the position must correspond to two hands (buying and selling with one hand). This is the relationship between liquidation and volume.

If the contract is close to delivery, people often choose to close their positions and switch to the far-month contract, then the activity (volume) of the month will decline. If there are many positions (transactions), then the volume is large and the positions are reduced.