Google Mobile First indexing and Desktop Simplified: What is Responsive Design?
The words “Website Design” are surrounded by a lot of jargon these days such as “Responsive Design, “Mobile Ready, “Mobile Friendly”, and the like. They all pretty much mean the same thing, however, let's break it down a bit so it’s a little clearer.
Responsive design means a website will adjust itself to be easily viewed on the device which is being used. For example, when viewing a website on a desktop, the site will align one way, however when moving to a mobile device, that same website reassembles its content making it simpler to see, navigate and use on that mobile device. On the desktop, the logo may be large and in the top left corner, the navigation is all spelled out and sprawling across the screen with a big photo of a mountain climber underneath the navigation and the hero intro text. That same website on a mobile device will show the logo centered, the navigation as 3 small lines that drop down when one clicks on it, the big mountain climbing photo has resized itself and the hero content is a bit larger and a bit more spread out.
This responsive design has responded according to your device. Note this is not a different website or a separate webpage. It's the same site, same page, same content just an alternative view.
Think of it like a rubber band. A rubber band stretched all the way out would represent a desktop view - the information is spread out with room to view the different nuances that make up a rubber band. Now we push the rubber band in until it starts folding in on itself. It gets all jumbled and it’s up to the web design team to get the rubber band to fold nicely so all of it can be seen.