Magento 2.1.x Notice: Magento 2.1.18 is the final 2.1.x release. After June 2019, Magento 2.1.x will no longer receive security patches, quality fixes, or documentation updates. To maintain your site's performance, security, and PCIPayment Card Industry: Refers to debit and credit cards and their associated businesses. compliance, upgrade to the latest version of Magento. The Magento User Guide 2.1.x remains available in PDF for Open Source and Commerce.
Magento Connect is Magento’s original marketplace for Magento extensions. There are hundreds of extensions and themes available from all over the world. Magento out-of-the-box supports a few of the most popular ones. However, community members are developing and publishing new extensions in order to extend Magento with various new features.