This references the way the layout of the content of the page changes at specific breakpoints. For example, in our mobile sizes, usually our content lines up under each other for a one column layout. As the page gets wider, the content may shift to a two-column layout and so forth.
Quote:
Keeping up with the device landscape is a full time job. I take my dog outside to poop only to come back and find that 17 new Android devices have been released. — Brad Frost