What is Responsive Websites (RWD) ?

The websites are designed in a way that it can adapts to the users viewing device. That is, website designed with responsive layout can be viewed in desktop computers, laptops, tablets and mobile phones almost visually similar in designs.

And also it has the ability to dynamically modify the size of the contents to be visible in smaller screens without any scrolls or abrupt breaks in page. Traditional old styled websites do not have this feature and it makes users to scroll left and right for each line of reading.