Front Month
The nearest-expiry futures contract with the highest liquidity and trading volume at any given time.
The front month (or lead month) is the active futures contract closest to expiration. Because it is the nearest delivery, it tends to carry the most open interest and tightest bid-ask spreads — making it the default choice for active traders.
As expiry approaches and traders roll forward, the front-month title passes to the next contract in the cycle. For equity index futures (ES, NQ, YM, RTY) this happens roughly 7–10 days before the current front-month expires.