Some store cards have special deals like 'buy now and pay nothing for a period of up to 2 to 3 years', which can be very tempting.
These are useful if you need to buy something urgently and you're sure you can pay it off within the interest-free period, but if you can't, you're likely to be slugged with rates of well over 20% interest on the debt at the end of it.
Similarly, some store cards have 'interest free for 12 months!' offers, but if you miss a single payment during that period, you will start being charged interest.
High rates of interest apply to these accounts and, your debt is more than likely to be substantially higher than you expected!