Flex Grid layout is most appropriate to the components of an application, and small-scale layouts, while the Grid layout is intended for larger scale layouts. Most importantly, the flex box layout is direction-agnostic as opposed to the regular layouts (block which is vertically-based and inline which is horizontally-based). While those work well for pages, they lack flexibility (no pun intended) to support large or complex applications (especially when it comes to orientation changing, resizing, stretching, shrinking, etc.). The main idea behind the flex layout is to give the container the ability to alter its items' width/height (and order) to best fill the available space (mostly to accommodate to all kind of display devices and screen sizes). A flex container expands items to fill available free space, or shrinks them to prevent overflow. Material Grammi have implemented three layout systems, giving users the ability to use them all in one project as well as use any of them in their projects.