CSS Grid is a two-dimensional layout system that handles both rows and columns simultaneously. Unlike Flexbox (one-dimensional), Grid excels at page-level layouts.
Display: grid creates a grid container. grid-template-columns defines column tracks: 1fr 2fr 1fr creates three columns. grid-template-rows works similarly for rows.
The gap property adds spacing between items without affecting outer margins. grid-area names items for template placement. repeat() and minmax() create responsive grids: repeat(auto-fit, minmax(300px, 1fr)).
Named grid areas create readable layouts: grid-template-areas: "header header" "sidebar main" "footer footer".
Grid and Flexbox complement each other. Use Grid for page layout and Flexbox for component-level alignment. Modern CSS combines both for maximum flexibility.