Adding to Michaela's great Answer, whenever you hear responsive design which you do a lot have the
following in mind. That making design responsive does not necessarily mean fitting the "entire" application on the user's screen. It means:
- intelligently pruning amount of information displayed based on the domain and your web-site needs
- making adjustments to the design to improve the users' experience while using the application based on the device they use
The main focus is on the users' experience of course. For example, if you open a web application on desktop, you may consider going all guns blazing and displaying a lot of information and pictures in the available screen with each component occupying optimal space. But, when you switch to a mobile device, you should not try to squeeze all the information into the limited real estate on screen.
Instead you should choose to
- drop out the less important chunks of information;
- reduce the number of processor-heavy components (elements that need to be frequently updated/redrawn/re-calculated); and
- reduce textual content to only highlight extremely important content
Saying the above, there is no hard rule out there about how to design your webpage and a specific path everyone should follow for their webpage. In fact, understanding this complexity and being able to design a notch website that is what makes a UI/UX designer/developer one of the best out there.