Flexbox is a CSS layout mode that aims to simplify responsive layout development. Flexbox layouts use two types of elements: flex containers and flex items. Flex containers have a primary axis (called the main axis) and a secondary axis (called the cross axis). Flex items are nested inside flex containers and can be aligned, sized, scaled, and ordered relative to the main or cross axis of the container. The visual order of flex items on the screen is independent of their HTML source order.
Classic DEV Post from Feb 8