You have a very nice website that appears great on your PC or MAC. You talk about it and it's very good. Your customers and friends consult with their smartphones and tablets and there ... it's the drama! Your site is not optimized for display on these media; worse still, your visitors, who have to play with their zoom to hope to read something, are agitated and leave the site. The "RWD" for "Responsive Web Design" - "Adaptive Design" in good French - is today "THE" essential technology in web projects. It consists of automatically adapting the layout of your website, regardless of the size or resolution of the visitor's screen, so that it becomes flexible and elastic (not the visitor ... your site!). Everything reorganizes automatically, the columns adjust, move or disappear, the images resize, the menus change ... This avoids having to create a site by terminal: a high resolution website, a website for Ipad, a site for Iphone and / or Android, etc ... The Responsive Web Design therefore offers you a unique, flexible and adaptable site! Moreover, the behavior that a mobinaute can have will not be the same as that of a surfer or a user of tablet ... These profiles use the Internet in different ways, in places, conditions and moments "The Mobile in the subway, the PC at work and the tablet before the dodo" (study of ComScore - 2013)! Your website must therefore be able to adapt so that mobile users can visit the same site, organized differently according to the terminal it owns (Apple iPad / iPhone, Google Nexus ...). This is called "improving the user experience". RWD figures & consequences Responsive Web Design improves branding. In June 2013, 25.1 Million French mobile users are equipped with a smartphone and more than 95% of them have connected to the Internet via their mobiles. Moreover, only about 10% of the million most visited sites are accessible via mobile. These figures speak for themselves about the fact that Responsive Web Design is synonymous with added value, competitive advantage and the interest for you to invest in a site including such technology. Responsive Web Design creates wealth. Indeed, the cost and the time of realization of a site in "Responsive Web Design" is much less than for the design of several sites adapted to each terminal.