Sites crafted with a responsive design simply adapt to the user's viewing environment (mobile, tablet, laptop etc). Such sites are designed in a way that all of the content, images and structure of the site remains the same on any device. Users that visit such sites don't have to fool around with zooming while surfing the sites.
If you own a site and would love to provide easy reading and navigation with a minimum of resizing and scrolling—across a wide range of devices, you should consider Responsive Web Design. The practice consists of a mix of flexible grids and layouts, images and an intelligent use of CSS media queries.
With responsive design, your site will have just one URL and the same HTML across all devices. It makes your site to be mobile friendly without the need of creating another site specifically developed for mobile users. You won't also have to worry about using the likes of mobstac, mobilepress to create mobile version of your site.
You can check if your website or blog is responsive or not at : www.responsinator.com
The site helps you quickly get an indication of how your responsive site will look on the most popular devices. All you just need to do is to enter your site URL and click "GO".
Whenever I redesign a Blogger blog to be responsive, I use the site to check the responsiveness of the blog. You can check what OgbongeBlog looks like on different devices here.
Use Responsinator to test your blog and let me know if your site is responsive or not. If you know other Responsive web design testing tools, kindly share via comments.
NB: You can also preview your site responsive design at : http://mattkersley.com/responsive/