SBI introduced virtual card for SBI net banking users. Other banks may also be providing Virtual Card, because I have listened about virtual card before SBI. Virtual card, by all the banks may be working the same way.

A virtual card is also known as Electronic Card or e-Card. Virtual card gives an extra layer of security for your credit or debit card. It works the same way as real debit or credit card works but it is virtual (not physical). And your actual card (plastic card) info will be safe from merchants. Virtual card has only card number so it is secure and makes your real card secure. There are some of the information about this card.

Virtual card is valid up to maximum 48 hours.
Card creation and online transaction only will be done after One Time Password (OTP) is sent to your mobile.
You can use this card to pay from any net banking enabled account.
Card can be created for any round amount from 100 to 50,000.
You do not need to apply for it, you need net banking to create virtual cards.
There is no interest on the use of this card.
Only VISA cards are accepted at this time.
A virtual card can be used only one time
Anywhere can be used where online purchase is enabled.
This can be used only for domestic purpose to make INR payment, Nepal and Bhutan also included.
After the transaction card will expired and card life is maximum 48 hours after the creation.
You can create as many as card in a day.

How to create virtual card in SBI?

Login to your online banking account www.onlinesbi.com and click on requests tab.

Now select State Bank Virtual Card

Now enter the amount and select an account if there is only one account, it will be selected automatically.

And Click on generate

Now you will get 8 digit password on your mobile number. Once you enter the 8 digit number successfully on the screen the card will be de-activated and unusable.

You can read the FAQ here.

Here is a PDF demo in detail of the same.