Drupal Commerce transforms Drupal into an eCommerce platform that lets e-retailers and developers easily design and implement very flexible features and user experiences. The design of Drupal Commerce frees e-retailers to focus on innovating and growing their businesses rather than on reinventing the wheel. Developers can use Drupal Commerce to implement highly tailored eCommerce systems without having to laboriously work around a set of assumptions.
Drupal 7 introduced a new system for customizing content in a very flexible way. Drupal Commerce core systems leverage this by implementing their own entities and fields relating to products, line items, orders, customer profiles, and payment transactions. In other words, eCommerce and general content are fully integrated and can be used as inputs to interact with each other.
A wide variety of modules has been contributed to Drupal Commerce since its inception. The features and functionality covered include shipping quotes for physical products, stock control for limited-quantity products, file downloads, coupons, an address book, and more — the list is constantly growing.
The Drupal Commerce core is compatible with Drupal-based solutions known as distributions. Commerce Guys' Commerce Kickstart for example, is designed to accelerate the installation and configuration of Drupal Commerce. Drupal developers have contributed additional feature-rich, use-case specific distributions like MartPlug, designed for smaller scale merchants, and Open Deals App, made for deals sites like Groupon.
While Drupal Commerce has its own unique qualities, it fully retains the benefits of Drupal. Drupal Commerce core systems are completely compatible with Drupal 7 technologies, modules, best practices, and skills. Also, Commerce Guys is actively involved in the development of Drupal, and the Drupal and Drupal Commerce communities work closely with each other.