The storage devices in the computer or connected to the computer are known as secondary memory of the computer. It is non-volatile in nature so permanently stores the data even when the computer is turned off. The CPU can't directly access the secondary memory. First the secondary memory data is transferred to primary memory then CPU can access it.
The hard disk, optical disk and pen drive are some of the popular examples of secondary memory or storage of computer.
It is a rigid magnetic disc that is used to store data. It permanently stores data and is located within a drive unit.
It has a plastic coating. The data in optical disc is recorded digitally and the recorded data is read with laser that scans its surface.
It is a compact secondary storage device. It is connected to a computer through a USB port to store or retrieve data.