First off what is responsive web design?
Well, simply put it is a website that is built to adapt across multiple devices and screens. This is accomplished via HTML5 and CSS3. The result enables the layout to respond to the environment of the user.
Think back to before the Apple iPhone. Sites then were built with a fixed width. The experience was mainly expected to come from desktops and laptops. But that Apple iPhone was such a success that people were carrying a mini computer in their pocket that had a browser. We know the number of iPhones sold was huge which was followed by Android devices. Then came the iPad and other tablets. This led to multiple different size screens and devices. Thus, responsive design is very important to have within your website.
If your current website is not responsive there could be lost opportunity. Think about the number of times you decided to look something up on your smart phone because it sits right there in your pocket or constantly in your hand (Pokemon GO!). That action is done when someone thinks about your business/brand. It is a user experience you do not want to lack.