Responsive website design, you don't have to have worry about having different websites for various devices or making sure that your site runs properly on a mobile device.
A responsive design simply means a website that has been constructed so that all of the content, images and structure of the site remain the same on any device. For example, when a user accesses a site on their desktop, they are getting the full view of the site. But when that same user goes to visit the site from their smartphone or tablet, the site will retract to fit on the smaller screen.
Selling products online
In its simplest form e-commerce is the buying and selling of products and services by businesses and consumers over the Internet.