credit card

Any security professional will tell you that attempting to retrofit security to a system is invariably expensive and seldom works. Just as the cost of change in any project goes up exponentially with time, the cost of adding security to a system late in the piece, in an unplanned manner, is usually prohibitive.

1. Never ever provide your credit card details to anyone as a result of following a link in an email (don't do this over the phone either) only do this if you have accessed a trusted site or service by your own actions.(i.e. you have typed the correct address for your internet banking)