Futures and options are called derivatives instruments. they are unlike cash market where the contract is signed today for a settlement in a future date.
In futures the settlement is done in full.
In option one can settle with a margin. There are two options: call and put. In both the buyer has rights . In the former the buyer has rights to sell and in the buyer has the to sell.
The difference in the strike price and the market price is the profit. In both options the buyer has the rights, the seller has no rights , but the seller gets a premium amount for the risk taken,