What is online backup ? Are they free ?

Backup of critical data is very crucial.Media devices like external hard-disk,cds,dvds are one choice .But that brings in two problems

• extra cost involved for buying the backup devices
• additional overhead for transporting them and safeguarding them.

"Online backup" is the solution :)
.Sometime we feel some big media files (eg an event video) to be shared among friends .It is not possible to send several GBs of files over mails . I feel online back up serves you to share large volumes of data .It will be also useful in scenarios where you work in  some remote computer and have large volumes of data, to be used when you reach office next day .In that case you can just upload your data to these online cloud data centers :)
Let me list some of the online storage services

• DropBox 
• Windows Sky Drive
• Mozy
• IDrive

Most of the back up services allow you to have free acess with limited storage after which you have to pay a substantial amount .But for personal use free access will be good enough i guess :)