E-commerce is the term used to describe electronic processing of buying items over the internet. For a standard e-commerce shop, this involves users viewing the items (images, description, price) and adding them to a virtual 'basket' online. After finalising their choices, users will normally enter their contact details into web forms and then their credit card / debit card to complete the purchase.
When building a website which takes credit cards, you should ensure the payment pages are set up with SSL. This means that the credit card data is encrypted while it is being used.
For example, the image to the right shows the first page of our checkout process for weetons.com. The padlock on the browser (in this case Google Chrome) shows that this page has been encrypted with SSL and is safe to proceed.