It depends on the debit card. I have both Visa Electron and Maestro, and they have 16 digits, CVV number and they behave like a credit card with 3D Secure when doing online purchases, while taking the money from the account right away.
There's also multifunction credit and debit cards (Mastercard and Maestro, or the Visa equivalent). They are branded like credit cards with a tiny Maestro logo on their backside, so I had to explain and ask the cashier in a grocery store in Amsterdam to try it as it would magically work as a debit card.
It depends on the debit card. I have both Visa Electron and Maestro, and they have 16 digits, CVV number and they behave like a credit card with 3D Secure when doing online purchases, while taking the money from the account right away.
There's also multifunction credit and debit cards (Mastercard and Maestro, or the Visa equivalent). They are branded like credit cards with a tiny Maestro logo on their backside, so I had to explain and ask the cashier in a grocery store in Amsterdam to try it as it would magically work as a debit card.