Drupal Commerce is a suite of modules written for Drupal 7 that enable you to create flexible, full-featured e-commerce sites. It is best described as an e-commerce framework as opposed to an out of the box shopping cart system. At the time of writing, Drupal 8 had not been released, but there is a roadmap available for the release of Commerce for Drupal 8 (http://www.drupalcommerce.org/roadmap).
Like Drupal itself, the Commerce framework components provided can be combined and extended to create any kind of e-commerce site, so you are not restrained by the default capabilities of the system.
The project is headed by Ryan Szrama of Commerce Guys; a French/American company dedicated to developing and supporting the Drupal Commerce platform. Drupal Commerce 1.0 was officially launched at DrupalCon London in 2011.
Unlike some other open source platforms, there are no premium or paid versions of Drupal Commerce. What you download from http://www.drupal.org/project/commerce is everything you need to get started.
The core Drupal Commerce download consists of the following modules:
Commerce (core module)
Cart
Checkout
Customer
Line item
Order
Payment
Price
Product
Product pricing
Product reference
Tax
The system was designed using a small core philosophy: the core modules only contain the components considered essential for every e-commerce site. For example, the shipping functionality is not included in core since it isn't necessary that every system has physical goods to ship. The rationale behind the system is to make no assumptions about the business logic of the system being built—rather it provides an extensible framework for development.
There are many modules available on Drupal.org that extend Drupal Commerce for different use cases. We will discuss some of them in this book.
Drupal Commerce exceeded 230,000 downloads in July 2013 and is used to power some high-profile and high-volume websites.