How are u everyone?
I am Margaret and I am a newbie to web design. I have recently read an article about web design and it was stated there that one of the factors in web design is responsive web designing.
I wonder what is its importance in the web and in mobile phones and how can I learn about it?
Thanks!
Hi margaretHofer. Welcome to the forums. 
Responsive design is a new trend, and is spurred on by the proliferation of mobile devices. Big, wide, cluttered layouts are not really good enough any more as more and more people are accessing content on small screens. Responsive design is one answer to this.
It was more or less introduced by this article a few years ago: http://alistapart.com/article/responsive-web-design/
Which spawned this book, which is worth reading: http://www.abookapart.com/products/responsive-web-design
There’s a ton to read online, too, so time to get reading!
Lots of clients are noticing this mobile trend and requesting it of their web designers, especially when they examine their visitor stats and learn that more and more of them are visiting the site on their mobile phone. Sites have seen an uptick in sales when the ordering has been made mobile-friendly. You definitely should look into RWD.
Welcome to the forums
“Responsive” design isn’t something new, web pages have always been responsive - see the first ever web page at http://info.cern.ch/hypertext/WWW/TheProject.html - it’s responsive
It’s only in recent years have designers chosen to restrict page widths and so on… but yes start reading about it!