A fixed deposit will mature at the end of the specified period chosen by the investor.
The investor can take the initial amount invested at this point of time and use the funds for some other purpose.
The other option available for the investor is to continue with the fixed deposit for some more time period.
This continuation of the fixed deposit is known as a rollover as the deposit continues.
The rollover can be for same period as the initial fixed deposit or the investor can also change it to some other period.