Responsive Web design is the approach that suggests that design and development should respond to the user's behavior and environment based on screen size

Responsive Web design is the approach that suggests that design and development should respond to the user’s behaviour and environment based on screen size, platform and orientation.

Responsive Web Design makes your web page look good on all devices (desktops, tablets, and phones). Responsive Web Design is about using HTML and CSS to resize, hide, shrink, enlarge, or move the content to make it look good on any screen: Try it Yourself » Note: A web page should look good on any device!

[Responsive Web Design is tied in with utilizing HTML and CSS to consequently resize, conceal, shrivel, or amplify, a site, to make it look great on all gadgets.

Responsive web design term used for mobile-friendly web design. If your website automatically changes UI while opening in mobile or tablet than its called responsive web design.