ES tracks the S&P 500 index. Each contract is $50 x the index level, ticks in 0.25 points ($12.50), and trades from Sunday evening to Friday afternoon with a brief daily pause. The micro version, MES, is $5 x the index.
It is the benchmark for US equity direction and the most common product among futures day-trading and prop-firm traders.
Example: ES at 5,000 has a notional-value of $250,000. A 20-point day is $1,000 per contract, or $100 on MES.
Related: nq, micro-futures, tick-value, index, notional-value