Until recently, Internet based card transactions have been classified as ‘card-not-present’ and ‘no signature present’ so it has been virtually impossible to prove that the actual cardholder is the person performing the payment transaction at an Internet merchant site.
The result? 78% of all e-commerce chargebacks are from ‘unauthorised transaction’ reason codes commonly referred to [...]

What is 3-D Secure Payer Authentication?
Payer authentication enables all parties in an e-commerce payment transaction to transmit confidential and valid payment data, and provides verification to the merchant that the buyer is the authorized owner of a particular card account.
3-D Secure has been named by VISA and MasterCard because there are 3 interoperability domains involved [...]