A responsive website is one that "responds" to the size of screen it is being displayed on. So, a responsive website will appear differently on a mobile phone than a laptop or desktop computer. Building a responsive website is also a recommended practice that we include in our White Hat SEO Tips.
- Makes your website accessible on different screen sizes.
- Google generally prefers to list responsive websites in search results.
- Eliminates need to build a mobile app for reaching a mobile audience.
Google has a page speed tester application that allows you to not only see how fast your page loads, but also see how your website displays on mobile phones.