When you are ready to pay by credit card after choosing the items or services you want to buy, always verify if you have entered a secured web page to provide you financial information.
Have a look at the URL in the navigation bar at top of the page:
If the page starts with 'http://www', you are not on a secured web page and should not provide sensitive data.
If the page starts with 'https://www' then you can proceed further with your order.
By convention, URLs that require an SSL connection start with https: instead of http.
SSL stands for Secure Sockets Layer. It is a protocol for transmitting encrypted private documents via the Internet such as credit card numbers