The breakthrough technology by which the HTML layout of a webpage automatically fits the width and height of any screen device is called Responsive Web Design. Furthermore, the layout can be made to flow seamlessly on any device, with the CSS's help written for that particular device. From a technical point of view, the HTML generated remains the same for all kinds of devices. It is the CSS that plays an all-important role in managing each device. Here's an example to explain how it works: a homepage slider with a width of 960 pixels on a laptop or a desktop gets automatically resized to 300 pixels for iPhones and similar devices! Back-End or Front-End You do not need a special server or hosting to run responsive websites. Since it is on the browser that the responsiveness comes about. It has everything to do with CSS3 and Media Queries. Media Queries form the main aspect of responsive web design. But what we are discussing here is how it impacts a WordPress theme. Google Media Queries and learn all that is there to be learned on it. ROI on using Responsive Web Design with Wordpress If you build your site based on a Responsive Web Design with WordPress. You are bound to get a greater Return on Investment for sure. This is because your site becomes equally viewer-friendly across screen sizes from desktop, laptop, or tablet devices to even smartphones like iPhone, Galaxy S, and other Android Phones. And you can do all this in one go. You needn't approach your web developer again for a mobile-friendly site as a single development process takes care of a site that fits all screens. Really no catch Yes indeed! There are no glitches in such a development. However, you might require some enhancements or device-exclusive functionalities based on the requirements of the people who want to build the site. On occasions, developers also may point these out. To cite an example, there are special events in touch-screen devices called "Swipe" and "Tap. Which you will not find in a non-touch-screen device. A developer can come up with great functionalities for a mobile device-friendly site. But it may cost a little more than a conventional site. Teamwork is the key for a great WordPress theme with a Responsive Theme Developing a responsive website with wordpress requires a different work culture altogether. A designer or a developer alone cannot do much and it is the synergy that both bring by discussing the project and implementing it that will do the trick. Why WordPress? Google Trends reveals that WordPress was the most popular CMS in January 2012. WordPress is so designedly friendly that any newbie designer without much knowledge of PHP can design a theme on it. With a bit of help from WordPress developers, a designer who can put in creative inputs can produce amazing outputs. This is why the ThemeForest website creates many WordPress themes with responsive web designs for sale. One wouldn't be surprised if all WordPress themes in the future come with a responsive design.