Drupal Commerce is the leading flexible eCommerce solution for Drupal, powering over 60,000 online stores of all sizes.
Note: 8.x-2.x is in beta. It is already usable for production websites and upgrades between versions are supported. Bugs are still expected. Please report bugs in the issue queue.
Use Composer to get Drupal + Commerce with all dependencies.
composer create-project drupalcommerce/project-base mysite --stability dev --no-interaction
See the install documentation for more details.