Responsive design is a digital solution that responds to the user's context and behavior by taking into account the different viewports. During Sketching, Wireframing and Prototyping, we always keep in mind that concept, design for the widely used screen sizes. In most cases, we follow the mobile first approach, which is a quite self-explanatory term: we start off by designing for mobile phone, and later convert the designs for tablet and desktop sizes. This approach let us focus on the most important elements, and results in a cleaner, streamlined design. It should be mentioned, that in some cases, there is no need for mobile versions, for example an architecture software or a complex accounting program is probably intended for desktop usage.