Responsive websites have been around for a while but unless you are in the design-, web- or marketing business chances are you are just going “huh?”
About 10 years ago Websites just needed to work on a desktop computer. You would build your website for a medium sized screen and that was that.
With the introduction of smartphones phones and later Ipads you really can’t get away with a one size fits all anymore.
A responsive website is a website that changes shape, letter and image size to always have an optimal viewing experience no matter what kind of device you are using.
Are you not sure if your website is responsive or not? Test it!