An option which gives the holder the right to buy a specified quantity of a physical underlying asset, such as a commodity, at the strike price specified by the option.
The holder will only exercise the option if it is beneficial for the holder to do so, based on the difference between the strike price and the price of the underlying asset at the maturity of the option.
A similar option over a non-physical underlying asset.
In practice many options are cash-settled by a payment, if relevant, by the writer (or seller) of the option to the holder, at the maturity date of the option.
There will be a payment if the underlying asset price is favourable for the option holder, compared with the strike price of the option.
Options over non-physical underlying assets are always cash-settled.
Foreign exchange call options
A foreign currency call option is the option to buy a specified quantity of the base currency in the currency pair, at the strike rate specified in the option.
Interest rate options
'Borrowers' options' hedge against a rise in interest rates.
For options over forward rate agreements, this is a call option.
Call options over short-term interest rate futures contracts are 'lenders' options'.
These hedge against a fall in interest rates.