If you're selling products or services online, you want your website to look like a store, not a blog. WooCommerce, from WooThemes, allows you to set up an online e-commerce site easily using WordPress. There are other e-commerce options for WordPress, but WooCommerce is the undisputed leader, and there is very little reason to use any other e-commerce solution.

WooCommerce is available in both free and paid versions, with several optional paid extensions, such as additional shipping modules and a fancy drag and drop shopping cart widget. The free version will allow you to set up a basic shopping cart within your WordPress installation and accept PayPal and credit card payments. However, WooCommerce will not serve as a substitute for a dedicated shopping cart such as Magento, which can painlessly handle tens of thousands of products, and manage thousands of transactions. WooCommerce is for smaller e-commerce stores with lower volume.

Download the plugin from https://wordpress.org/plugins/woocommerce/.