A debit card is linked to your current account and is used to pay for goods and services in the UK, abroad and online. The amount of the purchase is debited from your available balance on the same day. However it can sometimes take a few days for the funds to be debited from your account. Debit cards also allow you to withdraw money at cash machines or get cashback in shops that offer that service. Nearly all debit cards in the UK are Visa branded, but there are also Maestro cards.
More information is available in the debit card section of The UK Cards Association website.