Computer is an electronic machine which is very helpful for us in many ways. All the data in the computer is stored in digital format and the data are stored in binary values one and zero. Generally the data in the computer is stored in any of the storage media like hard disk.  The hard disk is a small storage device which is generally available in different sizes. The hard disk have two connectors which is for connect with data cable and another one for connect with power cable. Inside the hard disk we have magnetic disks to store data.  The hard disk is the primary one for storing digital computer data.

Next to hard disk many people prefer compact disk to store data. The compact disk is also known as cd and in a typical cd we can store data up to 650 Mb of data. In the cd we can store documents, movie file, music files and etc. The cd rates differ from the quality of the cd and now we also have DVD which is capable of storing large number of data. Then in recent years the USB flash drives are very popular among people because of its simplicity.