The full name of stock index futures is stock price index futures, which can also be called stock index futures and futures index. It refers to the standardized futures contract with the stock index as the subject matter. The two sides agreed that on a specific date in the future, they can buy and sell the underlying index according to the size of the stock index determined in advance. As a type of futures trading, stock index futures trading has basically the same characteristics and processes as ordinary commodity futures trading.
The essence of futures is to sign long-term contracts with others to buy and sell goods (or stock indexes, foreign exchange, interest rates) in order to achieve the purpose of maintaining value or making money.
If you think the futures price will go up, go long (buy and open positions), go up (sell) and close positions, and earn: price difference = close positions-open positions.
If you think the futures price will fall, short (sell the position), fall (buy) and close the position, and earn: price difference = opening price-closing price.