First, let's assume you have absolutely no idea of what we're talking about. Perfect! And, for you smarty pants out there who do: nicely done! Put simply, responsive web design takes into account the website may be viewed by desktop and mobile devices. It further provides that some features that work on a desktop browser may not be supported by a mobile device. So why is this a big deal (which it is)?
First, and foremost, is that you should make sure that all of your site's visitors have the same or equal experience, that all of your content displays correctly and it's easy to navigation. With more and more people using their smartphones to search the web, errors and omissions on your website could cause you to lose business.
Second, it is important to consider that desktop and mobile visitors may have different needs. Consider that mobile users may be trying to find your location or contact you by phone, is your phone number or directions easy to find? Responsive web design can also add special features for mobile users, such as "click to call", where your contact phone number works like a hyperlink and instantly initiates a call from the viewer's phone.
Mobile-friendly shrinks your website to fit small screens. Responsive design displays
your site customized to fit the screen, no matter the size.
Lastly, and most important is that the biggest search engine in the world, yep, Google has, for quite some time, given higher rankings for sites that are mobile-friendly. While you may think this effects only mobile search results, which is reason enough, but it also is a factor on non-mobile search indexing. Google recognizes your website as being very user friendly, and rewards you for taking the extra effort to be consistent, not matter the viewing platform.
If you've never taken the time to view your site on a phone or tablet, try it out. Does it look how you expect. Is anything missing or taking up too much space on the screen? It might be time to seriously consider updating your site to be mobile search ready using the advantage and power of responsive web design.