The "E-Commerce Cart" is a so-called "satellite" module of the "E-Commerce" module: the former only serves a purpose in conjunction with the latter, since its sole aim and function is showing your online shop visitors the status of their shopping cart (empty, with what/how many products, etc.) on a website created with the extension "Customize your platform"
The image above shows the "E-Commerce Cart" module inserted in a website: in the left column, regardless of the page currently being viewed, the cart's status is displayed.
Websites using this module
This module, in its different forms, is used among others by these content management system-powered websites: