Fluid grids are at the very core of responsive design. Grids allow you to align elements on your page and lay them out in a visually appealing way, following a certain hierarchy.
Media queries have existed since the early 2000s, but it wasn’t until 2012 that they became a W3C recommended standard. Like fluid grids, media queries represent a cornerstone technology behind responsive web design.
Responsive web design works rather well when you work with nothing but text. However, modern websites include a lot of media such as images and videos.