CSS Grid Layout is a powerful layout system in Cascading Style Sheets that allows web designers to create complex and responsive web layouts easily. It uses a two-dimensional grid-based approach, enabling designers to arrange elements in rows and columns. This flexibility makes it simple to create various layouts without relying on floats or positioning. With CSS Grid, developers can define grid containers and specify how child elements should be placed within the grid. This system supports features like grid lines, areas, and gaps, making it easier to manage spacing and alignment. Overall, CSS Grid Layout enhances the design process and improves website responsiveness.