At its core, Commerce is a set of Drupal 8 modules, which in turn depend on other best-of-breed modules and libraries.

The following Drupal contrib modules are used:

• Address - Provides functionality for storing, validating and displaying international postal addresses.
• Entity - Extends Drupal 8's entity API with additional features.
• State Machine - Provides code-driven workflow functionality.
• Inline Entity Form - Provides a widget for inline management of referenced entities.
• Profile - Provides configurable user profiles, used for customer profiles.

The following PHP libraries are used:

• commerceguys/intl - An internationalization library powered by CLDR data. Handles currencies, currency formatting, and more.
• commerceguys/addressing - An addressing library, powered by Google's dataset. Stores and manipulates postal addresses.
• commerceguys/zone - A zone library. Zones are territorial groupings mostly used for shipping or tax purposes.
• commerceguys/tax - A tax library with a flexible data model, predefined tax rates, powerful resolving logic.

The Drupal Console command-line tool.