To store copies of the files other than the hard disk on a medium is known as computer backup. The main reason for making computer backups is computer protection against the event if something occurs for damaging the files that cannot be used any longer. Through our back ups, we can restore these files, in case we have back ups for the files.

There are various formats in which computer back ups can be made. One of the traditional ways of computer back ups of the files was the floppy disk. Anyhow, these floppy disks have become obsolete now.  When you enter a computer store, it is common not to see even a new computer including a floppy disk drive. Floppy disks can hold approximately only 1.4 megabytes of data, whereas there are many more formats that can hold more than this.

CD-Rs are CD-ROMs and can hold up to 800 megabytes of data and you can write onto it actually. There are also CD-RWs on which you can write more than once. The other one becoming common these days are the DVD burners and DVD-R this can hold approximately 4.7 gigabytes or 4700 megabytes. 

One of the new technologies used these days and has a computer support is the key drive, which are very small and are removable drives. They are similar to the size of a key chain and majority of them are designed to be operated as key chains. These can hold a sizeable amount of data up to gigabytes, not as much as typical DVD-R.
The other thing you can use for backups is to make online backups for the files. It includes inserting the files of computer onto an online server that can be accessed from any other system when connected to the internet. This permits you to not get bothered with physical media like CD-ROMs or key drives while backing up the data still in a safe place. Back up is strong tools and keeps your data and computer protected .