CSS Grid Layout (aka “Grid”), is a two-dimensional grid-based layout system that aims to do nothing less than completely change the way we design grid-based user interfaces. Flexbox is intended for simpler one-dimensional layouts, not complex two-dimensional ones (Flexbox and Grid actually work very well together). Grid is the very first CSS module created specifically to solve the layout problems we’ve all been hacking our way around for as long as we’ve been making websites.
Source: https://css-tricks.com/snippets/css/complete-guide-grid/