Magento 2.0.18 is the final 2.0.x release. After March 2018, Magento 2.0.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.
Your store’s themeA package that contains graphics and appearance information, and customizes the look and feel of the store. is like window dressing that can be changed for a season or promotion. In this section of the guide, you will learn about page layouts, and how to apply a new theme to your store.
A theme is a collection of files that determines the visual presentation of your store. Your Magento installation initially has two themes available; the Luma theme with sample data and a blank theme. Both are responsive themes that adjust the display for different devices. In addition, there is a growing selection of themes available “off the shelf” on Magento Connect and Marketplace. When you first install Magento Commerce 2.0, the design elements of the store are based on the theme that is designated as the “Default” theme.