CSS Grid has full support in all modern browsers - Chrome 57+, Firefox 52+, Safari 10.1+, and Edge 16+, covering over 97% of global browser usage. No vendor prefixes are required today. For very old browsers a Flexbox fallback can be provided using @supports to detect grid support and serve an appropriate layout.

repeat() is a shorthand for repeating a track definition a set number of times. For example, grid-template-columns: repeat(4, 1fr) is equivalent to 1fr 1fr 1fr 1fr. It also accepts auto-fill and auto-fit keywords, which tell the browser to create as many tracks as will fit the container - useful for responsive grids with no media queries.

CSS Grid is a two-dimensional layout system built into CSS that lets you position elements into rows and columns simultaneously. Unlike Flexbox, which works along a single axis at a time, Grid gives you direct control over both dimensions at once, making it ideal for building full page layouts, dashboards, image galleries, and any design where items need to align both horizontally and vertically. You enable it by setting display: grid on a container element.