One of the most appealing aspects of responsive web design is that a responsive website can provide a great user-experience across many devices and screen sizes. A site that works well on any resolution, on any browser, on any devices will provide a better and more consistent user-experience.
Easier to Manage
Having a separate desktop and mobile site requires having separate SEO campaigns, separate design effort and seperate management. with responsive website no need to keep different people for different devices, no need to keep different copies of website.Increasing your reach to tablet and mobile audiences
Increase sales and conversion rates
Increase your visibility in search engines
Technically, responsive design is built using fluid grid layouts, flexible images and CSS media queries. Instead of setting fixed pixel widths, the layout is defined in relative units so columns, images and text reflow automatically to fit the available screen width. Media queries then let the same page apply different styling rules at different breakpoints, for example stacking a three-column layout into a single column on a phone, or hiding a desktop sidebar on a tablet. All of this runs from one single HTML/CSS codebase, so there is no separate mobile-only version of the site to keep in sync.
This "one codebase, many devices" approach matters for businesses for a few practical reasons. Maintaining one responsive site is cheaper and faster than maintaining a separate desktop site and a separate mobile (m.) site, since every content update, design change or new page only needs to be made once. It also avoids duplicate-content issues that can hurt search rankings, and it means every visitor, whatever device they land on, gets the same branding, navigation and information rather than a stripped-down mobile experience.
Google and other search engines also favour mobile-friendly, responsive pages in search results, and a well-optimised responsive layout typically loads faster on mobile networks than a heavier desktop-only design forced onto a small screen. Since the majority of web traffic today comes from phones and tablets, a responsive layout is now the standard approach for business, e-commerce and portfolio websites rather than an optional upgrade.