Every future contract is defined by a set of common characteristics. These characteristics are:
It is the asset on which the future contract refers to. In that sense we have futures on oil, futures on gold, silver etc.
It is a predefined date in which the underline asset must be delivered. The transaction will take place among a buyer and a seller (short seller). Both of them kept their contracts opened until the last trading date because their goal is the actual delivery of the asset, unlike a speculator who will close his/her position before the last trading date in order to profit from a rise or decline of the future price.
Last trading date
It is the last date that a futures contract is being trading. Anyone who doesn’t want physical delivery of the underline asset must close his position until this date.
Contract size & measurement unit
Depending on the underline asset, every future contract has a different size and a different measurement unit. For example a future in stocks has a size of 100 shares/contract, a future in oil has a size of 1000 barrels/contract, a future in gold has a size of 100 ounces/contract (in NYMEX).
Futures current price
Futures contracts are trading constantly during a certain period of time every day or all day. So, their prices are constantly changing, just like stocks. For example let’s take the WTI crude oil future with delivery after 3 months trading in NYMEX. It can open at $97/barrel and like a stock its price is changing all the time during the session, at least as long as it has sufficient liquidity. It can rise as high as $99, fall as low as $96 and close at $98, or follow every other possible scenario.
The price of a future contract is similar to the spot price of the underline asset but not exactly the same, at least until the last trading day. It is lower or higher (more or less) by a certain amount which is called basis.
It is the cash that someone must deposit to the clearing house of the transaction, as a guarantee that he/she fulfil the obligations arising from the contract. It is a percentage applied on the value of the position and it is different depending on the underline asset, its price volatility, the stock exchange or even the broker.
For example if someone is long (or short) 1 WTI crude oil contract with value $98,000 ($98/barrel x 1000 barrels/contract) and the initial margin requirement is 20%, then he/she has to deposit $19,600 ($98,000×20%) in cash in order to open the position.