All contacts can then easily be restored any time by simply opening *.VCF (vCard) backup file in the iPhone/iPod Touch/iPad Mail app. (3rd party Mail apps may not support vcf files.) This is a standard feature of iOS platform. (and same for Android platform)

So if you need to restore your contacts:

1) Open Mail app on your device (iPhone, iPad or iPod touch) 
2) Find the message including backup file sent previously to yourself
3) Tap on the attachment named (MyContactsBackup*.vcf) 

4) Finally tap on the "Add All XXX Contacts" option for restore contact to your Address Book.



Important: You can’t restore your contacts from CSV files same way. CSV is not a backup a file, it’s just an export file. You need to convert .CSV file to .VCF file first.