What is frontend ecommerce?

When someone is talking about the "front end" of ecommerce they are referring to the user interface. Front-end website is to look good so as to attract as many visitors as possible.

Some of the major open source carts are Magento, Oscommerce, Zen Cart and Xcart...

Openwave provides end-to-end E-Commerce solutions for clients who look to launch and maintain a professional and effective Online Store.