Hi to all
Why responsive web design is require...?

So that users with smart phones or small tablets will get an easier to use version of the page layout and not need to keep zooming in and out to get at bits of it. Links should also then be easier to click on as well.

fixed web sites work, ONLY on the device they were laid out on, look llike craqp on every other.

responsive design, using relative dimensionin in em or % adjusts to window size, screen resolution, device capability and user preferences
12px text vanishes on a screen with 267px/inch
1em text is visible on all devices
Blind freddy sets his basefont to 2inch high so he can readd it. em & % adjust, px pt pica do not
fixed size, pushes content offscreen in part windows, users do not scoll sideways, they leave

now a days ever user is browsing internet on their smart phones, so if a website is not resopnsive then user will migrate to other website. This will become a drawback to website.

iquallsama,

Today more than ever it is smart to consider building a responsive website especially if your product, service or information is directed at the masses. Here is a link to a quick read on Why Responsive Web Design is Important for your website. Enjoy!