Storefront is a free theme for WordPress created by Automattic.
Storefront is the perfect theme for your next WooCommerce project. Designed and developed by WooCommerce Core developers, it features a bespoke integration with WooCommerce itself plus many of the most popular customer facing WooCommerce extensions. There are several layout & color options to personalise your shop, multiple widget regions, a responsive design and much more. Developers will love its lean and extensible codebase making it a joy to customize and extend. Looking for a WooCommerce theme? Look no further.
(Description "Storefront" Theme from wordpress.org)
You can download Storefront for free via the provided download link and include it into your themes folder of your WordPress installation. Also you can directly search for it in the WordPress admin interface in the themes section and install and activate it from there.
More information, screenshots and reviews of Storefront Theme can be found here.